HK1252011B - Merging active group calls - Google Patents

Description

Merge Active Group Calls

Declaration of priority

This application claims priority to U.S. Patent Application No. 14/754,023, filed June 29, 2015, which is hereby incorporated by reference in its entirety.

Technical Field

The present disclosure relates to data transmission in a wireless communication system, and more particularly to merging active group calls.

Background Art

In some cases, a push-to-talk (PTT) service can provide an arbitration service for two or more users participating in a communication. For example, a user in a group call can request permission to send media, such as voice, video, or other multimedia content. In some cases, a user can request permission by pressing a button on a device, which sends a request to a server. The server can determine whether the user permission to send is granted and send an authorization message to the user. Examples of PTT services may include mission-critical PTT (MCPTT) services that may be applicable to mission-critical scenarios. In some cases, the MCPTT service may use the Third Generation Partnership Project (3GPP) transport communication mechanism provided by the Evolved Packet System (EPS) architecture to establish, maintain, and terminate the actual communication path between users. In some cases, the MCPTT service may use non-3GPP access technologies and architectures (e.g., based on a scheduler and/or administrator interface). Examples of PTT services may also include non-mission-critical PTT services.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is an example wireless communication system for merging active group calls, according to an embodiment.

FIG2 illustrates an example ad hoc PTT group call.

FIG3 illustrates an example pre-scheduled PTT group call.

FIG4 illustrates an example chat PTT group call.

5 is an example communication system for merging active group calls, under an implementation.

6A and 6B are data flow diagrams illustrating example processes for merging active group calls, according to an embodiment.

FIG7 is a flow chart illustrating an example method for merging activity groups, according to an embodiment.

8 is a data flow diagram illustrating an example process for providing information of PTT clients in a merged group call, according to an embodiment.

9 is a block diagram of an example computer that may be used to merge active group calls, according to an embodiment.

Like reference numerals and designations in the various drawings indicate like elements.

DETAILED DESCRIPTION

The present disclosure relates to merging active group calls. In some cases, multiple PTT groups may be temporarily merged. For example, when an event occurs in an area, different PTT groups may be merged so that members of these different PTT groups can communicate with each other. In some cases, ad hoc groups or pre-arranged groups can be formed to include different PTT groups. An ad hoc group call is a group call of group members included in the request to initiate the call. A pre-arranged group is a group with a pre-defined list of member groups and a call is initiated by including a URI associated with the group in the request to initiate the call. Users in these different PTT groups can be invited to join the ad hoc group call or pre-arranged group call. After the event, the ad hoc group call or pre-arranged group call can be ended.

In some cases, two or more PTT groups have active group calls and wish to merge their active group calls into a merged group call. Merging calls using an ad hoc group call or a pre-scheduled group call may lose the state of the active group call. For example, the ad hoc group call or pre-scheduled group call method may invite all members of the PTT group, including members not currently participating in the active group call. Additionally, information about the active group call (e.g., queue information and pending requests) may be lost in an ad hoc group call or a pre-scheduled group call.

In some cases, a group type called a chat group can be used for PTT calls. In an ad hoc or pre-arranged group, members are invited to join the group call at the start of the call. However, in a chat group, group members must request to join (similar to how they dial in to a conference).

In some cases of pre-arranged chat groups, in addition to having a list of authorized members who will be invited or allowed to join the group call, the authorized members may have to be affiliated with the group to indicate their current interest in being invited to the group call. Because some affiliated members may not be able to participate in the call (e.g., due to being out of radio coverage or the user not accepting the invitation to join), the active participants in the group call may be a subset of those who are affiliated with the group.

In some cases, it may be necessary to merge a plurality of chat groups or prearranged groups, and the authorized member from other groups may attempt to join the chat group call (for example, by sending an invitation to the PTT server to join the chat group call by the server supervisor) that merges. Yet, the supervisor server of the chat group call may not access the group information of other PTT groups of its active group call in charge in different servers, for example, member list. Therefore, the supervisor server may not invite or authorize the member from other PTT groups to join the chat group call. In addition, the authorized member of the chat group may not know that this chat group has been merged into the temporary chat group call. Therefore, it is necessary to have a method and/or system to indicate that the chat group has been merged into the temporary chat group call to all authorized members, or to redirect the member who attempts to join the original chat group and/or to notify it that they may need to join the temporary chat group call that merges now.

FIG1 illustrates an example wireless communication system 100 for merging active group calls, according to an embodiment. For example, a first group of PTT clients may already be participating in a first active group call, and a second group of PTT clients may already be participating in a second active group call. A primary push-to-talk (PTT) server (also referred to as a first PTT server) may receive a request to merge the first active group call with the second active group call. The primary PTT server may send a first invitation message to the first group of PTT servers. The first group of PTT servers may host the first active group call. In response to the first invitation message, the primary PTT server may receive a first response message from the first group of PTT servers. The primary PTT server may send a second invitation message to the second group of PTT servers. The second group of PTT servers may host the second active group call. In response to the second invitation message, the primary PTT server may receive a second response message from the second group of PTT servers. The primary PTT server may host the merged PTT group call. The first group of PTT clients and the second group of PTT clients may participate in the merged PTT group call.

In some embodiments, the primary PTT server may receive a host media burst request message from the first group of PTT servers. The host media burst request message may indicate a pending request to send media. The pending request is received at the first group of PTT servers before receiving a request to merge the first active group call with the second active group call. The primary PTT server may send a host media burst grant message. The host media burst grant message may grant the pending request. In some cases, the host media burst request message may indicate a multimedia broadcast/multicast service (MBMS) bearer to be used by at least one PTT client in the first group of PTT clients for the first active group call. In some cases, the host media burst request message may indicate a timestamp, queue position, or priority of the pending request.

In some embodiments, the master PTT server may send a first subscription request to the first group PTT server. In response to the first subscription request, the master PTT server may receive a first notification message. The first notification message may identify the first group of PTT clients. In some embodiments, the first notification message may include metadata for the first group of PTT clients. In some cases, the metadata may indicate one or more pending requests to send media from members of the first group of PTT clients. The pending requests may be received at the first PTT server before the first invitation message. In some cases, the metadata may indicate at least one of a timestamp, a queue position, or a priority for each of the pending requests. In some cases, the metadata may indicate a multimedia broadcast/multicast service (MBMS) bearer used by at least one PTT client in the first group of PTT clients for the first active group call. In some cases, the first notification message may identify authorized members of the group, affiliated members of the group, or participants in the group call.

The primary PTT server may send a second subscription request to the second group of PTT servers. In response to the second subscription request, the primary PTT server may receive a second notification message. The second notification message may identify the second group of PTT clients. In some cases, the primary PTT server may receive a subscription request from the first group of PTT servers. In response to the subscription request, the primary PTT server may send a first notification message. The first notification message may identify the second group of PTT clients. In some cases, the primary PTT server may send a second notification message. The second notification message may indicate that the PTT client has joined or left the merged group call.

In some embodiments, the second notification message may include metadata for the second group of PTT clients. In some cases, the metadata may indicate one or more pending requests for sending media from members of the second group of PTT clients. The pending requests may be received at the second PTT server before the second invitation message. In some cases, the metadata may indicate at least one of a timestamp, a queue position, or a priority of each of the pending requests. In some cases, the metadata may indicate a multimedia broadcast/multicast service (MBMS) bearer used by at least one PTT client in the second group of PTT clients for the second active group call. In some cases, the second notification message may identify authorized members of the group, affiliated members of the group, or participants of the group call.

In some embodiments, the primary PTT server may be a different server than the first group of PTT servers or the second group of PTT servers. In some embodiments, the primary PTT server may be the same server as the first group of PTT servers or the second group of PTT servers.

Merging active group calls according to the methods and systems described herein can provide one or more advantages. For example, queued requests from the request queues of the first and second group calls are transmitted to a primary PTT server. The request queues may include requests from PTT clients requesting permission to send media. The primary PTT server can obtain information about pending requests received from the first and second group calls prior to forming the merged group call. The primary PTT server can process these pending requests in the merged group call. The merged group call can include PTT clients currently participating in the first and second group calls, while excluding PTT clients not currently participating in the first and second group calls. In some cases, the number of authorized members in a group may be very large, but the number of actual attached members and active participants in the calls may be much smaller. This provides the advantage of not disrupting ongoing group calls when a reunion occurs. Furthermore, the primary PTT server can obtain information about pending requests in the first and second group calls and can process these pending requests in the merged call, consolidating pending requests from the first group call with pending requests from the second group call based on timestamps, relative queue positions, and/or priorities of the requesting participants from the two group calls. Furthermore, using the MBMS channel to send media data from the primary PTT server to the PTT clients in the merged group call can save resources and improve the efficiency of the communication system.

At a high level, the example wireless communication system 100 includes a wireless communication network 120 that includes or is communicatively coupled to a first group of PTT servers 102, a second group of PTT servers 112, and a master PTT server 110. The example wireless communication system 100 also includes user equipment (UEs) 106a-c and UEs 116a-b. In some cases, each of the UEs 106a-c and UEs 116a-b may include a PTT client. The wireless communication system 100 may also include UEs that are non-wireless devices, such as a PTT dispatcher that can connect to a wireless network using fixed access technologies such as Ethernet or a wireless local area network (WLAN). A PTT client may refer to an application, a set of applications, software, a software module, hardware, or a combination thereof that can be configured to communicate with a PTT server for PTT services. As shown, UEs 106a-c are included in a first group 104, and UEs 116a-b are included in a second group 114. In some cases, the first group 104 has an ongoing first group call participated in by the UEs 106a-c, and the second group 114 has an ongoing second group call participated in by the UEs 116a-b.

The example wireless communication system 100 also includes a first group PTT server 102 hosting a first group call, a second group PTT server 112 hosting a second group call, and a master PTT server 110 that performs floor control arbitration for the merged group calls. In some cases, a PTT server (e.g., the first group PTT server 102, the second group PTT server 112, or the master PTT server 110) can provide participation functionality, control functionality, termination functionality, or a combination thereof for a PTT service.

In some cases, the PTT server can provide participation functionality for an associated PTT client. In these or other cases, the PTT server may be in the same service domain as the associated PTT client. An example of a service domain may be a network or a portion of a network. For example, the PTT server may be an application server in the PTT client's home core network. The PTT server can access the configuration and settings of the associated PTT client. The PTT server can also perform media replication, traffic optimization, or a combination thereof for the associated PTT client.

In some cases, a PTT server can provide control functions for a group call. In these or other cases, the PTT server can act as the host for the group call. The PTT server can perform floor control arbitration functions, such as media burst control or floor control functions, to receive and arbitrate requests to send media in a group call. The PTT server can also perform media replication functions, traffic optimization functions, or a combination thereof for the group call.

In some cases, the PTT servers that perform the participation function and the control function can be co-located in the same entity. For example, the first group of PTT servers 102 can perform both the participation function and the control function. Alternatively, the PTT servers that perform the participation function and the control function can be located in the network architecture separately. In some cases, as shown in the figure, the first group of PTT servers 102, the second group of PTT servers 112 and the main PTT server 110 can be located in the same wireless network. Alternatively, the first group of PTT servers 102, the second group of PTT servers 112 and the main PTT server 110 can be located in different wireless networks.

In some cases, the PTT server and PTT client can be implemented according to the PTT over Cellular (PoC) or Push to Public Safety (PCPS) standards. The PoC and PCPS standards were developed by the Open Mobile Alliance (OMA) to provide PTT services via cellular networks based on the Internet Protocol (IP). In some cases, the PTT server and PTT client can be implemented according to the Mission Critical PTT (MCPTT) standard developed by 3GPP.

In operation, master PTT server 110 receives a request to merge UEs in first group 104 with UEs in second group 114. The request may include an identifier for first group 104 and an identifier for second group 114. Master PTT server 110 sends a first invite message to first group PTT server 102. The first invite message may include an indication that, if the first group is involved in an active call, master PTT server 110 requests to serve as the master PTT server for the call, should send requests for the floor, and will control which PTT clients of the first group are granted the floor. In some cases, the indication may be encoded using Extensible Markup Language (XML). Alternatively, or in combination, the indication may be encoded in one or more existing or new header fields in the invite message. In response to the first invite message, master PTT server 110 receives a first response message. The first response message may indicate that first group 104 has an active group call. In some cases, the indication that the group is currently in an active group call may be encoded using Extensible Markup Language (XML). Alternatively, or in combination, the indication may be encoded in one or more existing or new header fields in the response message. The first response message may indicate that the first group PTT server 102 accepts the request of the primary PTT server 110 to serve as the primary PTT server for the call. In some cases, the indication of the first group PTT server 102 accepting the request of the primary PTT server 110 to serve as the primary PTT server for the call may be encoded using Extensible Markup Language (XML). Alternatively, or in combination, the indication may be encoded in one or more existing or new header fields in the response message. The primary PTT server 110 sends a second invitation message to the second group PTT server 112. The second invitation message may include an indication indicating that, if the second group is involved in an active call, the primary PTT server 110 requests to serve as the primary PTT server for the call and should send requests for the floor and control which PTT clients of the second group are granted the floor. In some cases, the indication may be encoded using Extensible Markup Language (XML). Alternatively, or in combination, the indication may be encoded in one or more existing or new header fields in the invitation message. In response to the second invitation message, primary PTT server 110 receives a second response message. The second response message may indicate that second group 114 has an active group call. The second response message may indicate that second group PTT server 112 accepts the request from primary PTT server 110 to serve as the primary PTT server for the call. In some cases, the indication that the group is currently in an active group call may be encoded using Extensible Markup Language (XML). Alternatively, or in combination, the indication may be encoded in one or more existing or new header fields in the response message. Primary PTT server 110 may perform floor control arbitration functions for the merged PTT group call, which may be participated in by UEs 106a-c and UEs 116a-b. First group PTT server 102 and second group PTT server 112 may send pending requests for first group 104 and second group 114 to primary PTT server 110. Primary PTT server 110 processes the floor control request for the merged group call and determines which PTT client in the first or second group is next granted the floor.

In some embodiments, the master PTT server 110 can create a request queue for the merged group call. In some cases, if the master PTT server 110 is the same server as the first group PTT server 102 or the second group PTT server 112, the existing request queue of the first group 104 or the existing request queue of the second group 114 can be updated or replaced with the request queue for the merged group call.

In some embodiments, the master PTT server 110 may contact the first and second group PTT servers 102 and 112 to notify them that it is the master PTT server. The first and second group PTT servers 102 and 112 may then send media and request queue information to the master PTT server 110. The group PTT servers 102 and 112 may also send information about the PTT clients in the group to the master PTT server 110, such as the roles, priorities, and privileges of the PTT clients. In some public safety use cases, the roles, priorities, or privileges of the PTT clients may depend on the type of event the PTT client is servicing or the overall transition role of the PTT client. The group PTT server may also send information to the master PTT server 110 indicating whether the PTT client is currently participating in the group call. The master PTT server 110 makes a determination and indicates to the first and second group PTT servers 102 and 112 the permitted PTT clients that are authorized to send media.

In some embodiments, a PTT client may prefer to have information about other PTT clients in a merged group call. To achieve this, the master PTT server 110 sends a subscription request to the group PTT servers 102 and 112. The group PTT server 102 or 112 may provide this information to the master PTT server 110 in a notification message. The master PTT server 110 may provide information about PTT clients in other groups to the group PTT server 102 or 112. The group PTT server 102 or 112 may provide this information to its managed PTT clients upon request. This is achieved by PTT servers 102 and 112 sending subscription requests to the master PTT server 110, and the master PTT server 110 providing this information to the master PTT server 110 in a notification message. In some embodiments, the PTT client may directly send a request to the master PTT server 110 for information about other PTT clients in the merged group call. The PTT client may obtain information about other PTT clients in the merged call from the master PTT server 110. In some implementations, the master PTT server 110 may indicate to the PTT client that it may request information for other PTT clients in the merged group call directly from the master PTT server 110 .

2-9 and the associated descriptions provide additional details of example implementations.

Turning to the general description of elements, a UE may be referred to as a mobile electronic device, user equipment, mobile station, subscriber station, portable electronic device, mobile communication device, wireless modem, PTT dispatch console, or wireless terminal. Examples of UEs (e.g., UEs 106a-c and UEs 116a-b) may include cellular phones, personal digital assistants (PDAs), smart phones, PTT dispatch consoles, laptop computers, tablet personal computers (PCs), pagers, portable computers, portable gaming devices, wearable electronic devices, or other mobile communication devices having components for transmitting voice or data via a wireless communication network. The wireless communication network may include a wireless link over at least one of a licensed spectrum and an unlicensed spectrum.

Other examples of UE include mobile and fixed electronic devices. A UE may include a mobile equipment (ME) device and a removable memory module, such as a universal integrated circuit card (UICC) including a subscriber identity module (SIM) application, a universal subscriber identity module (USIM) application, or a removable user identity module (R-UIM) application. The term "UE" may also refer to any hardware or software component that can terminate a user's communication session. Additionally, the terms "user equipment," "UE," "user equipment device," "user agent," "UA," "user device," and "mobile device" may be used synonymously herein.

The wireless communication network 120 may include one or more radio access networks (RANs), other access networks such as fixed Ethernet or IEEE 802.11 WLAN, a core network (CN), and external networks. The RAN may include one or more radio access technologies. In some embodiments, the radio access technology may be Global System for Mobile Communications (GSM), Interim Standard 95 (IS-95), Universal Mobile Telecommunications System (UMTS), CDMA2000 (Code Division Multiple Access), Evolved Universal Mobile Telecommunications System (UMTS), Long Term Evolution (LTE), or Advanced LTE. In some cases, the core network may be an Evolved Packet Core (EPC).

The RAN is the part of a wireless telecommunications system that implements radio access technologies such as UMTS, CDMA2000, 3GPP LTE, and 3GPP LTE-A. In many applications, the RAN includes at least one base station. A base station can be a wireless base station that controls all or at least some of the radio-related functions in the fixed portion of the system. A base station provides a radio interface within its coverage area, or cell, for UEs to communicate with. Base stations can be distributed throughout a cellular network to provide wide-area coverage. A base station communicates directly with one or more UEs, other base stations, and one or more core network nodes.

Although the elements of FIG1 are shown as including various component parts, portions or modules that implement various features and functions, these elements may also appropriately replace and include multiple sub-modules, third-party services, components, libraries, etc. In addition, the features and functions of various components may be appropriately combined into fewer components.

FIG2 illustrates an example ad hoc PTT group call. A system 200 for an ad hoc PTT group call may involve a PTT client 202 acting as a group call initiator, a plurality of PTT clients 204 a-c that will participate in the group call, and a PTT server 206. The group call initiator 202 may send an invitation message to the PTT server 206 to initiate the group call. The invitation message may include a list of PTT clients to be invited to the group call. The PTT server 206 then sends invitation requests 208 a-c to the PTT clients 204 a-c to form a group call 210.

FIG3 illustrates an exemplary pre-arranged PTT group call. A system 300 for a pre-arranged PTT group call may involve a PTT server 304, a PTT client 306 acting as a group call initiator, and a plurality of PTT clients 308 a-c that will participate in the group call. A list of PTT clients 302 of the pre-arranged group is pre-provided in the PTT server 304. The group call initiator 306 may send an invitation message to the uniform resource indicator (URI) of the group. The PTT server 304 hosting the group then sends an invitation message to the PTT clients 308 a-c in the pre-arranged group to form a group call 312.

FIG4 illustrates an example chat PTT group call. A system 400 for a chat PTT group call may involve a PTT server 404, a PTT client 406 acting as the group call initiator, and multiple PTT clients 408a-c that will participate in the group call. In a restricted chat PTT group call, a list of PTT clients 402 is pre-provisioned in the PTT server 404. A PTT client that wishes to join the group call sends an invite message or dial-in message 410a-c to the group's URI to form a group call 412. In a restricted chat PTT group call, the PTT server 404 hosting the group checks whether the requesting PTT client is in the pre-provisioned list. In an unrestricted chat PTT group call, there is no pre-provisioned list, and any PTT client can join. These long-standing, semi-permanent chat group calls are likely to be the type of group call commonly used by public safety agencies.

FIG5 is an example communication system for merging active group calls, according to an embodiment. System 500 includes a master PTT server 506, multiple group PTT servers 508a-e hosting group calls 502a-e, and a PTT client 510 acting as a scheduler. Scheduler 510 can send a request to master PTT server 506 to merge group calls 502a-e into a merged group call 504. Master PTT server 506 can send a request to group PTT servers 508a-e. Group PTT servers 508a-e can transmit a floor request queue to master PTT server 506. Group PTT servers 508a-e can transmit subsequent floor requests to master PTT server 506. Master PTT server 506 can create a floor request queue for merged group call 504 and authorize requests to send media. Authorization requests to send media can be sent to group PTT servers 508a-e.

In some embodiments, the new PTT server is designated as the primary PTT server 506 for the merged group call, and the PTT servers of the group calls 502a-e act as group PTT servers 508a-e. In some cases, one of the PTT servers of the group calls 502a-e is designated as the primary PTT server 506. The hosted PTT group call mechanism defined in OMA-TS-PoC System Description-V21 can be enhanced to allow the primary PTT server 506 to act as the moderator, and the group PTT servers 508a-e will function similarly to PTT servers in the hosted PTT call (see OMA-TS-PoC System Description-V21). The hosted media burst control message can be enhanced to allow the primary PTT server 506 to receive requests to send media and authorize requests from PTT clients in the merged group call.

In some embodiments, the merged group call can be split. For example, the scheduler 510 can send a request to the master PTT server 506 indicating that the merged group will be split. The master PTT server 506 can send a request to each of the group PTT servers 508a-e indicating that the merged group call will be split. The master PTT server 506 can provide the group PTT servers 508a-e with a request queue associated with each group. The master PTT server 506 can send a goodbye request to each of the group PTT servers 508a-e indicating that the master PTT server 506 will leave the call.

Figures 6A and 6B are data flow diagrams illustrating an example process 600 for merging active group calls according to an embodiment. The data flow diagram includes a group PTT control server X1 602. Group PTT control server X1 602 represents an application, a collection of applications, software, a software module, hardware, or a combination thereof that can be configured to provide control functionality for an active group call (e.g., active group call X1 as shown in Figures 6A and 6B). In some cases, a group of PTT clients (e.g., group X1) can participate in active group call X1. For example, as shown, group X1 can include PTT client A 606. The data flow diagram also includes a PTT participating server A 604. PTT participating server A 604 represents an application, a collection of applications, software, a software module, hardware, or a combination thereof that can be configured to provide participating functionality for PTT client A 606. In some cases, group PTT control server X1 602 and PTT participating server A 604 can be implemented on the same PTT server. In these or other cases, the messages between the group PTT controlling server X1 602 and the PTT participating server A 604 shown in the data flow diagram may be omitted.

The data flow diagram also includes a group PTT control server X2 612 that provides control functionality for the active group call X2. In some cases, another group of PTT clients (e.g., group X2) can participate in the active group call X2. For example, as shown, group X2 can include PTT client B 616. The data flow diagram also includes a PTT participating server B 614 that provides participation functionality for PTT client B 616. In some cases, group PTT control server X2 612 and PTT participating server B 614 can be implemented on the same PTT server. In these or other cases, the messages between group PTT control server X2 612 and PTT participating server B 614 shown in the data flow diagram can be omitted.

The data flow diagram also includes a master PTT control server 610, which provides control functionality for the combined group call of active group call X1 and active group call X2. In some cases, the master PTT control server 610 is a different server than the group PTT control server X1 602 or the group PTT control server X2 612. In some cases, the master PTT control server 610 is the same server as the group PTT control server X1 602 or the group PTT control server X2 612. In these or other cases, the messages between the group PTT control server X1 602 and the master PTT control server 610, or between the group PTT control server X2 612 and the master PTT control server 610, shown in the data flow diagram, may be omitted.

As shown in Figures 6A and 6B, prior to operation 1, both group calls X1 and X2 are in progress. At operation 1, PTT client A 606 sends a request to the master PTT control server 610 to merge the active group calls X1 and X2. In some cases, the request may be a referral request. This request may request the master PTT control server 610 to send an invitation message to each of group PTT control server X1 602 and group PTT control server X2 612, the invitation message including a join indication indicating that it requests to join the call and to serve as the primary floor control arbitrator for the merged group call. In some cases, the request may include an identifier for group X1 and an identifier for group X2. Examples of identifiers may include a uniform resource indicator (URI) or any other group identity indicator. In some cases, the URI may be a string used to identify the group. In some cases, the identifier may be included in the referral header field of the referral request. In some cases, the request may be sent by an authorized PTT client in group X1 or group X2 (e.g., PTT client A 606, as shown). Alternatively or in combination, the request may be sent by a dispatcher that is neither in group X1 nor in group X2. Alternatively or in combination, the request at operation 1 may be sent by the group management server based on creating a merged group of X1 and X2 in the group management server in order to merge the group calls of X1 and X2.

At operation 2, the primary PTT control server 610 sends an approval response to the PTT client A 606. In some cases, the approval response indicates that the primary PTT control server 610 has received the request.

At operation 3, the master PTT control server 610 sends an invite message to the group PTT control server X1 602. The invite message may include a join indication indicating that it is requesting to join the call and requesting to serve as the primary floor control arbitrator for the merged group call. The invite message may also include an identifier for group X1. The identifier for group X1 may be included in the request-URI field of the invite message. In some cases, the invite message may indicate that the sending PTT server will be the master PTT control server and the receiving PTT server will be the group PTT control server. The master PTT control server may also provide the group PTT control server with an address (e.g., an IP address) for forwarding media and requests to send media. In response to the invite message, at operation 4, the group PTT control server X1 602 sends a grant response to the master PTT control server 610. The grant response may include an indication that PTT control server X2 612 accepts the request by the master PTT control server 610 to perform floor control arbitration for the merged group call.

At operation 5, the master PTT control server 610 sends an invite message to the group PTT control server X2 612. The invite message may include a join indication. The invite message may also include an identifier for group X2. The identifier for group X2 may be included in the request-URI field of the invite message. In response to the invite message, at operation 6, the group PTT control server X2 612 sends an approval response to the master PTT control server 610. The approval response may include an indication that the PTT control server X2 612 accepts the request by the master PTT control server 610 to perform floor control arbitration for the merged group call.

At operation 7, the group PTT control server X1 602 sends a moderator burst request to the master PTT control server 610. The group PTT control server X1 602 uses the moderator burst request to send an indication of a pending request to send media to the master PTT control server 610. In some embodiments, the moderator burst request may include information about pending requests received at the group PTT control server X1 602 before receiving the invite message for the merged group call. The moderator burst request may include an indication of the identity of the PTT client that sent the pending request. The moderator burst request may also include information about the pending request. The pending request information may include a timestamp of the request, a priority of the request, and a queue position of the request. The timestamp may indicate the time the pending request was received. The priority may indicate the priority of the request, which may depend on the role and priority of the PTT client sending the request or the nature of the request (e.g., an emergency situation). The queue position may indicate the position of the pending request in the request queue. The group PTT control server X1 602 may maintain a request queue of pending requests from PTT clients in group X1. The group PTT control server X 1602 may also maintain multiple request queues of requests. In some cases, a moderator burst request message may include information on multiple pending requests.

In some embodiments, the moderator burst request may also include an identification of the MBMS bearer to be used by the PTT client that sent the pending request to receive media. The identification of the MBMS bearer may include a temporary multicast group identity (TMGI). By providing the MBMS bearer information, the master PTT control server 610 can send media directly to the PTT client without routing it through the group PTT control server X1 602. In some cases, the master PTT control server may establish a new MBMS bearer with a new key or a new TMGI and send an instruction to the PTT clients in the merged group to move the media transmission to the newly established MBMS bearer. Alternatively, the master PTT control server may utilize an existing MBMS bearer to deliver media to the merged group.

At operation 8, in response to the moderator burst request, the master PTT control server 610 sends a moderator burst request confirmation message to the group PTT control server X1 602 to confirm receipt of the moderator burst request. In some cases, the moderator burst request confirmation message can be sent using a Real-Time Control Protocol (RTCP) Application (APP) packet. Alternatively, or in combination, the media burst request message can be sent using a Binary Floor Control Protocol (BFCP).

At operation 9, the group PTT control server X2 612 sends a moderator burst request to the master PTT control server 610. The group PTT control server X2 612 uses the moderator burst request to send an indication of a pending request to send media to the master PTT control server 610. In some embodiments, the moderator burst request includes information about pending requests received at the group PTT control server X2 612 prior to receiving the invite message for the merged group call. The moderator burst request may include an indication of the identity of the PTT client that sent the pending request. The moderator burst request may also include information about the pending request, such as a timestamp of the request, a priority of the request, a queue position of the request, and an identifier of the MBMS bearer used by the PTT client that sent the pending request. At operation 10, in response to the moderator burst request, the master PTT control server 610 sends a moderator burst request acknowledgement message to the group PTT control server X2 612 to acknowledge receipt of the moderator burst request.

At operation 11, the group PTT control server X1 602 may send a moderator burst request to the master PTT control server 610 to indicate the second pending request of group X1 received at the group PTT control server X1 602 before the call merge. At operation 12, in response to the moderator burst request, the master PTT control server 610 sends a moderator burst request confirmation message to the group PTT control server X1 602.

At operation 13, the group PTT control server X2 612 may send a moderator burst request to the master PTT control server 610 to indicate the second pending request of group X2 received at the group PTT control server X2 612 before the call merge. At operation 14, in response to the moderator burst request, the master PTT control server 610 sends a moderator burst request confirmation message to the group PTT control server X2 612.

At operation 15, the group PTT control server X1 602 may send a moderator burst request to the master PTT control server 610 to indicate the third pending request of group X1 received at the group PTT control server X1 602 before the call merge. At operation 16, in response to the moderator burst request, the master PTT control server 610 sends a moderator burst request confirmation message to the group PTT control server X1 602.

6A and 6B , group PTT control server X1 602 has three pending requests before receiving the invite message for the merged group call, and group PTT control server X2 612 has two pending requests. Therefore, group PTT control server X1 602 sends three moderator burst requests to transfer the pending requests to master PTT control server 610, and group PTT control server X2 612 sends two moderator burst requests to transfer the pending requests to master PTT control server 610.

In some embodiments, the master PTT control server 610 may create a request queue for the merged group after receiving pending requests from the group PTT control server X1 602 and the group PTT control server X2 612. In some cases, the master PTT control server 610 may create the request queue for the merged group before receiving pending requests from the group PTT control server X1 602 and the group PTT control server X2 612. The master control server 610 may create the request queue for the merged group at any time after receiving a request to merge the group calls. By receiving information about the pending requests, such as timestamps, queue positions, and priorities, the master control server 610 may place these requests in a queue appropriately ordered with the pending requests in the active group calls X1 and X2 and process them accordingly.

The master PTT control server 610 may determine that the request from PTT client A 606 in group X1 is authorized. At operation 17, the master PTT control server 610 may send a host burst authorization message to the group PTT control server X1 602. The host burst authorization message may be sent using RTCP APP packets or BFCP. The host burst authorization message may include an indication of the PTT client authorized to send media. The group PTT control server X1 602 may obtain PTT client information from the host burst authorization message. After determining that PTT client A is in group X1, at operation 18, the group PTT control server X1 602 may send a media burst authorization message to the PTT participating server A 604, which may further forward the media burst authorization message to the PTT client A 606 at operation 19. After receiving the media burst grant message, the PTT client 606 may begin sending media to the group PTT control server X1 602, which may further forward the media to all PTT clients in the merged group call.

At operation 20, the master PTT control server 610 may also send a moderator burst grant message to the group PTT control server X2 612, which includes information about the PTT client that has been granted permission to send media. After receiving the moderator burst grant message, the group PTT control server X2 612 determines that the PTT client A that has been granted permission to send media is not in group X2. In response to this determination, at operation 21, the group PTT control server X2 612 sends a media burst get message to the PTT participant server B 614. The PTT participant server B 614 may further forward the media burst get message to PTT client B 616 at operation 22 to indicate that permission to send media has been granted to another PTT client in the merged group call. The media burst get message may indicate the identity of the PTT client that has been granted permission to send media. The media burst get message may be sent using RTCP APP packets or BFCP. In some embodiments, group PTT control server X1 602 and group PTT control server X2 612 may send a media burst get message to each PTT client in the merged group call except for the PTT client authorized to send media. In some embodiments, operations 17 and 20, as well as other operations, may be concurrent, simultaneous, or overlapping events.

At operation 23, PTT client B 616, which has media to send, sends a media burst request to group PTT control server X2 612 to request permission to send the media. At operation 24, group PTT control server X2 612 sends a moderator burst request to the master PTT control server 610 to indicate the request from PTT client B 616 requesting permission to send the media. In response to the moderator burst request, at operation 25, the master PTT control server 610 sends a moderator burst request confirmation message to group PTT control server X2 612 to confirm receipt of the moderator burst request. The master PTT control server 610 can grant permission for PTT client B 616 to send the media by sending a moderator burst authorization message to group PTT control server X2 612.

FIG7 is a flow diagram illustrating an example method 700 for merging active group calls. The method 700 may begin at block 702, where a primary push-to-talk (PTT) server, also referred to as a first PTT server, may receive a request to merge a first active group call with a second active group call. A first group of PTT clients may participate in the first active group call, and a second group of PTT clients may participate in the second active group call.

At block 704, the master PTT server may send a first invitation message to the first group of PTT servers. The first group of PTT servers may host the first active group call. In response to the first invitation message, at block 706, the master PTT server may receive a first response message from the first group of PTT servers. At block 708, the master PTT server may send a second invitation message to the second group of PTT servers. The second group of PTT servers may host the second active group call. In response to the second invitation message, at block 710, the master PTT server may receive a second response message from the second group of PTT servers. At block 712, the master PTT server may host the merged PTT group call. The first group of PTT clients and the second group of PTT clients may participate in the merged PTT group.

At block 714, the primary PTT server may receive a moderator media burst request from the first group of PTT servers. The moderator media burst request may indicate a pending request to send media. The pending request may be received at the first group of PTT servers before receiving the request to merge the first active group call with the second active group call. At block 716, the primary PTT server may send a moderator media burst grant message. The moderator media burst grant message may grant the pending request. In some cases, the moderator media burst request may indicate an MBMS bearer to be used by at least one PTT client in the first group of PTT clients for the first active group call. In some cases, the moderator media burst request may indicate a timestamp, queue position, or priority of the pending request.

8 is a data flow diagram illustrating an example process 800 for providing information of PTT clients in a merged group call according to an embodiment. The data flow diagram includes a master PTT control server 802, a group PTT control server X1 804 for an active group call X1, and a group PTT control server X2 806 for an active group call X2.

At operation 1, the master PTT control server 802 sends an invitation message to the group PTT control server X1 804. This is the same invitation message as in operation 3 of FIG. 6A . In response to the invitation message, at operation 2, the group PTT control server X1 804 may send an approval response to the master PTT control server 802. This is the same approval response as in operation 4 of FIG. 6A . At operation 3, the master PTT control server 802 sends an invitation message to the group PTT control server X2 806. This is the same invitation message as in operation 5 of FIG. 6A . In response to the invitation message, at operation 4, the group PTT control server X2 806 may send an approval response to the master PTT control server 802. This is the same approval response as in operation 6 of FIG. 6A .

At operation 5, the master PTT control server 802 may send a subscription request to the group PTT control server X1 804 to request information about PTT clients in the active group call X1. At operation 6, the group PTT control server X1 804 may send a notification message to the master PTT control server 802, providing information about the PTT clients in the active group call X1. In some cases, the notification message may include information about the PTT clients currently participating in the active group call X1. In some cases, subsequent notification messages may include information indicating that a PTT client has left or joined the active group call X1. At operation 7, the master PTT control server 802 may send a subscription request to the group PTT control server X2 806 to request information about the PTT clients in the active group call X2. At operation 8, the group PTT control server X2 806 may send a notification message to the master PTT control server 802, providing information about the PTT clients in the active group call X2. In some cases, the notification message may include information about the PTT clients currently participating in the active group call X2. In some cases, the subsequent notification message may include information indicating that the PTT client has left or joined the active group call X2. This enables the primary PTT control server 802 to obtain information about all PTT clients in the merged group call. The PTT client can obtain information about other PTT clients in the merged group call by sending a subscription request to the primary PTT control server 802 and receiving a notification message from the primary PTT control server 802.

Alternatively, or in combination, at operation 9, the group PTT control server X1 804 may send a subscription request to the master PTT control server 802 to request information about PTT clients in the active group call X2. At operation 10, the master PTT control server 802 may send a notification message to the group PTT control server X1 804, providing information about the PTT clients in the active group call X2. In some cases, the notification message may include the PTT clients currently participating in the active group call X2. For each group member, the notification message may include the member's identity, such as the member's Session Initiation Protocol (SIP) URI, and a status indicator. The status indicator may be set to "active" for members currently participating in the group call X2. For members not currently participating in the group call X2, the status indicator may be set to "inactive." For members who are attached but not currently participating in the group call X2, the status indicator may be set to "attached." In some cases, subsequent notification messages may include information indicating that the PTT client has left or joined the active group call X2. At operation 11, the group PTT control server X2 806 may send a subscription request to the master PTT control server 802 to request information about the PTT clients in the active group call X1. At operation 12, the master PTT control server 802 may send a notification message to the group PTT control server X2 806 to provide information about the PTT clients in the active group call X1. For each group member, the notification message may include the member's identity, such as the member's Session Initiation Protocol (SIP) URI and a status indicator. For members currently participating in group call X1, the status indicator may be set to "active." For members not currently participating in group call X1, the status indicator may be set to "inactive." For members who are affiliated but not currently participating in group call X1, the status indicator may be set to "affiliated." In some cases, the notification message may include the PTT clients currently participating in the active group call X1. In some cases, subsequent notification messages may include information indicating that the PTT client has left or joined the active group call X1. In some embodiments, the group PTT control server X1 804 and the group PTT control server X2 806 may have information about the PTT clients in the merged group call. The PTT clients of group X1 may obtain information about the PTT clients in the active group call X2 by sending a subscription request to the group PTT control server X1 804 and receiving a notification message from the group PTT control server X1 804. The PTT clients of group X2 may obtain information about the PTT clients in the active group call X1 by sending a subscription request to the group PTT control server X2 806 and receiving a notification message from the group PTT control server X2 806.

FIG9 is a block diagram 900 of an exemplary computer that can be used to merge active group calls according to an embodiment. The computer 902 shown is intended to encompass any computing device, such as a server, desktop computer, laptop/notebook computer, wireless data port, smart phone, personal digital assistant (PDA), tablet computing device, one or more processors within these devices, and/or any other suitable processing device, including physical and/or virtual instances of computing devices. In addition, the computer 902 may include a computer that includes input devices such as a keypad, keyboard, touch screen, microphone, voice identification device, other devices that can accept user information, and/or output devices that transmit information associated with the operation of the computer 902 (including digital data, visual and/or audio information or GUI).

The computer 902 can function as a client, a network component, a server, a database or other persistent device, and/or any other component of the system 100. For example, the computer 902 can be used to implement one or more functions of a PTT server or a PTT client. The computer 902 is shown communicatively coupled to a network 930. In some embodiments, one or more components of the computer 902 can be configured to operate within a cloud computing-based environment.

At a high level, the computer 902 is an electronic computing device operable to receive, send, process, store, or manage data and information associated with the system 100. According to some embodiments, the computer 902 may also include or be communicatively coupled with an application server, an email server, a web server, a cache server, a streaming data server, a business intelligence (BI) server, and/or other servers.

Computer 902 may receive requests from client applications (e.g., executed on another computer 902) over network 930 and respond to the received requests by processing the requests in an appropriate software application. Requests may also be sent to computer 902 from internal users (e.g., from a command console or through another appropriate access method), external or third parties, other automated applications, and any other appropriate entity, person, system, or computer.

Each of the components of computer 902 can communicate using system bus 903. In some embodiments, any and/or all components of computer 902 (both hardware and/or software) can interface with each other and/or with interface 904 on system bus 903 using application programming interface (API) 912 and/or service layer 913. API 912 can include specifications for routines, data structures, and object classes. API 912 can be either computer language independent or computer language dependent and can refer to a complete interface, a single function, or even a set of APIs. Service layer 913 provides software services to computer 902 and/or system 100. The functions of computer 902 can be accessible to all service consumers using the service layer. Software services such as those provided by service layer 913 provide reusable, defined business functions through defined interfaces. For example, the interface can be software written in Java, C++, or other suitable languages that provide data in Extensible Markup Language (XML) format or other suitable formats. Although shown as an integrated component of the computer 902, alternative implementations may show the API 912 and/or service layer 913 as separate components associated with the computer 902 and/or other components of the system 100. Furthermore, any or all portions of the API 912 and/or service layer 913 may be implemented as a subclass or submodule of another software module, enterprise application, or hardware module without departing from the scope of the present disclosure.

The computer 902 includes an interface 904. Although shown as a single interface 904 in FIG. 9 , two or more interfaces 904 may be used depending on the specific needs, desires, or specific implementations of the computer 902 and/or system 100. The computer 902 uses the interface 904 to communicate with other systems in a distributed environment (including within the system 100) connected to a network 930 (whether or not shown). Typically, the interface 904 includes logic encoded in software and/or hardware in an appropriate combination and operable to communicate with the network 930. More specifically, the interface 904 may include software supporting one or more communication protocols associated with the communication, such that the network 930 or the hardware of the interface is operable to transmit physical signals within and external to the system 100 shown.

Computer 902 includes a processor 905. Although shown as a single processor 905 in FIG9 , two or more processors may be used depending on the particular needs, desires, or particular implementation of computer 902 and/or system 100. Generally, processor 905 executes instructions and manipulates data to perform operations of computer 902. Processor 905 performs the functions required for merging active group calls.

The computer 902 also includes a memory 906 that stores data for the computer 902 and/or other components of the system 100. Although shown in Figure 9 as a single memory 906, two or more memories may be used depending on the particular needs, desires, or implementation of the computer 902 and/or system 100. Although the memory 906 is shown as an integral component of the computer 902, in alternative implementations, the memory 906 may be external to the computer 902 and/or system 100.

Application 907 is an algorithmic software engine that provides functionality based on the specific needs, desires, or specific implementation of computer 902 and/or system 100, particularly functionality required for merging active group calls. For example, application 907 may function as one or more of the components/applications described in Figures 1-9. Furthermore, while illustrated as a single application 907, application 907 may be implemented as multiple applications 907 on computer 902. Furthermore, while illustrated as being integral to computer 902, in alternative implementations, application 907 may be external to computer 902 and/or system 100.

There may be any number of computers 902 associated with the system 100 or external to the system 100 and communicating over the network 930. Furthermore, the terms "client," "user," and other appropriate terms may be used interchangeably as appropriate without departing from the scope of this disclosure. Furthermore, this disclosure contemplates that many users may use one computer 902, or that one user may use multiple computers 902.

Although operations are described in a particular order in the accompanying drawings, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, in order to achieve the desired results. In some cases, multitasking and parallel processing may be utilized. Furthermore, the separation of various system components in the above-described embodiments should not be understood as requiring such separation in all embodiments, and it should be understood that the described program components and systems may generally be integrated together in a single software product or packaged into multiple software products.

In addition, the techniques, systems, subsystems and methods described and shown as discrete or separated in various embodiments can be combined or integrated with other systems, modules, techniques or methods. Other items shown or discussed as being coupled to each other or directly coupled or communicating with each other can be indirectly coupled or indirectly coupled or communicated through some interface, device or intermediate component, whether electrically, mechanically or otherwise. Other examples of variations, substitutions and modifications can be determined and made by those skilled in the art.

While the foregoing detailed description has shown, described, and pointed out the basic novel features of the present disclosure as applied to various embodiments, it will be understood that various omissions, substitutions, and changes in the form and details of the systems shown may be made by those skilled in the art. In addition, the order of the method steps is not implied by the order in which they appear in the claims.

Claims (20)

1. A method comprising: A request for merging a first active group call and a second active group call is received at a first PTT server, wherein a first group of PTT clients participate in the first active group call, and the first PTT server acts as the talk control arbitrator in the first active group call before merging the active group call; and a second group of PTT clients participate in the second active group call, and the second PTT server acts as the talk control arbitrator in the second active group call before merging the active group call. A first invitation message is sent from the first PTT server to the first group of PTT servers, wherein the first group of PTT servers manages the first activity group calls; In response to the first invitation message, receive the first response message; A second invitation message is sent from the first PTT server to the second group of PTT servers, wherein the second group of PTT servers manages the second active group calls; In response to the second invitation message, receive the second response message; and The PTT group call is merged, wherein the first group of PTT clients and the second group of PTT clients participate in the merged PTT group call, and the first PTT server acts as the arbitrator for speaking control of the merged PTT group call. 2. The method according to claim 1, further comprising: Receive a host media burst request from the first group of PTT servers, wherein the host media burst request indicates a pending request for sending media, wherein the pending request is received at the first group of PTT servers before receiving the request for merging the first activity group call and the second activity group call; and Send a host media burst authorization message, wherein the host media burst authorization message authorizes the pending request. 3. The method of claim 2, wherein the host media burst request instructs a multimedia broadcast/multicast service (MBMS) carrier used by at least one PTT client from the first group of PTT clients for the first activity group call. 4. The method of claim 2, wherein the host media burst request indicates at least one of the timestamp, queue position, or priority of the pending request. 5. The method according to claim 1, further comprising: Send the first subscription request to the first group of PTT servers; In response to the first subscription request, a first notification message is received, wherein the first notification message identifies the first group of PTT clients; Send a second subscription request to the second group of PTT servers; and In response to the second subscription request, a second notification message is received, wherein the second notification message identifies the second group of PTT clients. 6. The method according to claim 1, further comprising: Receive subscription requests from the first group of PTT servers; and In response to the subscription request, a first notification message is sent, wherein the first notification message identifies the second group of PTT clients. 7. The method according to claim 6, further comprising: Send a second notification message, wherein the second notification message identifies the PTT client that joined or left the merged group call. 8. An apparatus comprising: Memory; and At least one hardware processor, communicatively coupled to the memory, is configured to: A request for merging a first active group call and a second active group call is received at a first PTT server, wherein a first group of PTT clients participate in the first active group call, and the first PTT server acts as the talk control arbitrator in the first active group call before merging the active group call; and a second group of PTT clients participate in the second active group call, and the second PTT server acts as the talk control arbitrator in the second active group call before merging the active group call. A first invitation message is sent from the first PTT server to the first group of PTT servers, wherein the first group of PTT servers manages the first activity group calls; In response to the first invitation message, receive the first response message; A second invitation message is sent from the first PTT server to the second group of PTT servers, wherein the second group of PTT servers manages the second active group calls; In response to the second invitation message, receive the second response message; and The PTT group call is merged, wherein the first group of PTT clients and the second group of PTT clients participate in the merged PTT group call, and the first PTT server acts as the arbitrator for speaking control of the merged PTT group call. 9. The device of claim 8, wherein the at least one hardware processor is further configured to: Receive a host media burst request from the first group of PTT servers, wherein the host media burst request indicates a pending request for sending media, wherein the pending request is received at the first group of PPT servers before receiving a request to merge the first activity group call and the second activity group call; and Send a host media burst authorization message, wherein the host media burst authorization message authorizes the pending request. 10. The device of claim 9, wherein the host media burst request indicates a multimedia broadcast/multicast service (MBMS) carrier used by at least one PTT client from the first group of PTT clients for the first activity group call. 11. The device of claim 9, wherein the host media burst request indicates at least one of the timestamp, queue position, or priority of the pending request. 12. The device of claim 8, wherein the at least one hardware processor is further configured to: Send the first subscription request to the first group of PTT servers; In response to the first subscription request, a first notification message is received, wherein the first notification message identifies the first group of PTT clients; Send a second subscription request to the second group of PTT servers; and In response to the second subscription request, a second notification message is received, wherein the second notification message identifies the second group of PTT clients. 13. The device of claim 8, wherein the at least one hardware processor is further configured to: Receive subscription requests from the first group of PTT servers; and In response to the subscription request, a first notification message is sent, wherein the first notification message identifies the second group of PTT clients. 14. The device of claim 13, wherein the at least one hardware processor is further configured to: Send a second notification message, wherein the second notification message identifies the PTT client that joined or left the merged group call. 15. A tangible, non-transitory, computer-readable medium containing instructions that, when executed, cause a computing device to perform operations, the operations including: A request for merging a first active group call and a second active group call is received at a first PTT server, wherein a first group of PTT clients participate in the first active group call, and the first PTT server acts as the talk control arbitrator in the first active group call before merging the active group call; and a second group of PTT clients participate in the second active group call, and the second PTT server acts as the talk control arbitrator in the second active group call before merging the active group call. A first invitation message is sent from the first PTT server to the first group of PTT servers, wherein the first group of PTT servers manages the first activity group calls; In response to the first invitation message, receive the first response message; A second invitation message is sent from the first PTT server to the second group of PTT servers, wherein the second group of PTT servers manages the second active group calls; In response to the second invitation message, receive the second response message; and The PTT group call is merged, wherein the first group of PTT clients and the second group of PTT clients participate in the merged PTT group call, and the first PTT server acts as the arbitrator for speaking control of the merged PTT group call. 16. The tangible non-transitory computer-readable medium of claim 15, wherein the operation further comprises: Receive a host media burst request from the first group of PTT servers, wherein the host media burst request indicates a pending request for sending media, wherein the pending request is received at the first group of PPT servers before receiving a request to merge the first activity group call and the second activity group call; and Send a host media burst authorization message, wherein the host media burst authorization message authorizes the pending request. 17. The tangible non-transitory computer-readable medium of claim 16, wherein the host media burst request indicates a multimedia broadcast/multicast service (MBMS) carrier used by at least one PTT client from the first group of PTT clients for the first activity group call. 18. The tangible non-transitory computer-readable medium of claim 15, wherein the operation further comprises: Send the first subscription request to the first group of PTT servers; In response to the first subscription request, a first notification message is received, wherein the first notification message identifies the first group of PTT clients; Send a second subscription request to the second group of PTT servers; and In response to the second subscription request, a second notification message is received, wherein the second notification message identifies the second group of PTT clients. 19. The tangible non-transitory computer-readable medium of claim 15, wherein the operation further comprises: Receive subscription requests from the first group of PTT servers; and In response to the subscription request, a first notification message is sent, wherein the first notification message identifies the second group of PTT clients. 20. The tangible non-transitory computer-readable medium of claim 19, wherein the operation further comprises: Send a second notification message, wherein the second notification message identifies the PTT client that joined or left the merged group call.