WO2000028699A1 - An improved private combined voice fax and data telecommunication system - Google Patents

Abstract

Private combined voice, fax and data telecommunication network (PVDTN) suitable for performing voice, fax and data communications between an organization's locations spread over a city, country and the world over a network of analogue and digital lines and point-to-point satellite links, comprising: transmission media between all major locations of the network and between major and minor locations in their regions, voice data private switches (VDPs), leased line modems for analogue leased lines and dial-up modems for analogue and long line analogue extensions whereby a common trunk arrangement of analogue trunk circuits of the voice-data private switches (VDPSs) is provided, which terminate on multiple vocoders of the fixed channel multiplexers and a VDPS by-pass arrangement which is used for providing fixed data pipes for direct and continuous LAN to LAN data link across a voice-data metropolian area network/voice data wide area network (VDMAN/VDWAN) without switching by using a dedicated part of the bandwidth of a leased line which is available between the two connected locations.

Description

AN IMPROVED PRIVATE COMBINED VOICE FAX AND DATA TELECOMMUNICATION SYSTEM This invention relates to an improved private combined voice, fax and, data telecorrmun icat ions network which facilitates voice, fax and data coπrmun icat ions on a single network connecting an organization's locations spread over a city, country, and the world, through analogue, digital, or a mixture of analogue and digital terrestrial leased lines, non-exchange leased lines or private wires, d i rect i onal i sed full duplex VHF, UHF radio links, multiple access radio relay (MARR), and point-to-point satellite links (used in case of long distance, inaccessible sites onl y ) .

For setting up a Company ' s /Or gan i zat i on ' s integrated information system (IIS), based on mechanized data gathering (MDG) at all Company /Organizat ion action points, a 100% secure, private communications backbone is required.

For this purpose, in the current state-of-the-art, the following options are available at present: (i) voice over data private networks (VODPN) using digital leased lines and fixed channel voice- data multiplexers, data routers, etc: (ii) private voice data telecom network PVDTN as described in Indian Patent No.176287. The PVDTN system is capable of setting up voice/ fax/data networks over analogue leased lines. It also mentions that when digital leased lines become available from DOT (Department of Tel ecorrmun icat ions ) and other PTT's (postage, telephone, and telegraph authorities) appropriate interfaces will be used to provide digital end-to-end connectivity, and eliminate the leased line modems. The currently available trunk interfaces for ISDN (integrated services digital networks) compatiable EPAXs (electronic private automatic exchanges) which form the VDPSs (voice-data private-switches) in the PVDTN system are either 2W or ΨW, E& , analogue trunk cards, or 2 MBPS (mega bytes per second) digital trunk cards to CEPT specifications of 30B+2D channels. Each B channel has a line speed or bandwidth of 6 KBPS (Kilo bytes per second), and each D channel has a line speed or bandwidth of 16 KBPS. The CEPT cards are generally used for distribution of telephone connections to housing and commercial complexes under the group dialing franchisee scheme of various PTTs .

LIST OF ACCOMPANYING DRAWINGS Fig.l. Shows the wide area and metropolitan area network topology of the invented system. Fig.2. Shows in detail the leased line connections to the VDPS trunks for analogue and digital leased lines, and also the tandem switching capability of the VDPSs.

Fig.3. Shows the detailed local area and metropolitan area connections of the VDPS and the trunk loop back system which facilitates data connectivity between the analogue and digital extensions of the same VDPS.

Fig.4. Shows the VDPS by-pass arrangement for forming fixes data pipes between LAN buses and also the details of the VDMAN connection through long line extensions, ASCS , and non-exchange leased lines or private wire circuits.

Figs.5. Shows the multiple access facility of the local HOST/SERVER computer. DOT and other PTTs in the world are now making available digitial leased lines in 64 KBPS, or multiples thereof. A 6 KBPS line is about 1.5 times more costly than an analogue leased line which has an effective data speed of 9.6 KBPS. A 128 KBPS line costs 1.8 times that of a 64 KBPS line. A 2 MBPS line costs 16 times the cost of a 64 KBPS line. To make any private network cost effective, it is, there- 0 fore, necessary to make the best use of available bandwidth .

While such digital leased lines are available between most major cities and large industrial towns, they are still not available for smaller towns which 5 continue to be served by analogue transmission system.

A trunk system has, therefore, been incorporated in the present invention which will enable the PVDTN system to make effective use of the presently available 64 KBPS lines cost effectively. This 0 comprises of analogue trunk cards of the VDPSs of the PVDTN system, which will terminate on multiple vecoders situated in ADPCM fixed channel multiplexers, the aggregate output of which will be connected to the 64 KBPS leased lines. Similar circuitry is 5 employed on either end of all 64 KBPS circuits. This type of connection splits the 64 KBPS circuits into multiple channels for simultaneous conrmunicat ions in any combination of voice/ fax/data. A maximum of eight channels are recommended , and can increase

•J_Q from 2,4,6, to 8. The larger the number of channels the lower the effective data speed. The number of channels a 64 KBPS is split into is, therefore, determined by the number of simultaneous channels required between any two locations and the acceptable data speeds on the universal switched channel.

By adding such a trunk system to the existing PVDTN system, the following benefits will be derived.

1. For one 64 KBPS digital line between points A & B, the system user will now have anything between 2 to 8 simultaneous channels of corrmun icat ion . The more the number of channels the higher the set-up cost and the lower the cost per channel, and the lower the fax/data speed. 2. The cost per channel of corrmun icat ion works out to be cheaper than the cost per analogue line. 3. Also the cost per channel, is cheaper than that for the type of digital leased lines envisaged in the PVDTN system of Indian Patent 176287. 4. The system user can now have simultaneous voice/ fax/data corrmunicat i ons between A and B locations even on a 64 KBPS leased line which is currently available at reasonable cost from various PTTs. 5. The tandem switching capability as claimed in the PVDTN system will with the help of this new universal channel mu 11 ipl iat ion technique, of the present invention, facilitate simultaneous corrmun icat ions between A, B, C, D, E, F, G, H, over the single digital link between A and B, and the analogue connections between A to C, D, E and B to F,G,H, as shown in Fig.2 of the accompanying drawings.

6. This new arrangement will, therefore, substantially reduce the cost of network build-up, compared to the present art of VODPN and also the PVDTN system described in Indian Patent No.176287.

7. The existing practice of building voice over data private networks (VODPNs), using digital leased lines, voice-data multiplexers, data routers, etc., are fraught with some inherent defects. Two types of multiplexers are in use. The fixed channel type has the problem that when any one channel either voice, or fax, or data, are not in use the bandwidth allocated to it lies idle and cannot be used for any other type of corrmunicat i on . However, there is no inter-channel interference, and if the above limitation is acceptable then voice/ fax/data corrmun icat ions can be integrated over a single network. To overcome the problem of wasted bandwidth, an adaptable bandwidth multiplexer was developed, but it brought with it the problem of inter-channel interference. Thus if voice is given a priority, and on-going data call gets interrupted as soon as a voice call is initiated. If data is given priority an on-going voice call gets chopped off as soon as a data call is initiated. If no priority is allocated chaos prevails. This type of multiplexer has, therefore, failed to integrate voice/ fax/data on a single network, and those who had tried it, have had to abandon the concept of integration and have had to settle for separate voice and data networks.

8. Since in the present invention fixed channel mu 11 i - plexers are being used, there is no inter-channel interference. And since by combining these with the VDPS, each fixed channel is suitable for either voice or fax or data corrmunicat ions , they are universal in nature. There is, therefore, no wasted bandwidth, as any free channel can be used for any type of corrmunicat ions switched through the VDPS. Thus true and unhindered integration of voice/ fax/data takes place through a single leased line network.

9. The new common trunk system of present invention, therefore, gives major economic benefits, and technical advantages over the system of private voice and data teleconrmuni cat ions network of 176287; and comb ined with the latter it overcome s the deficiencies of the existing voice over data private networks using digital leased lines only, voice-data multiplexes, data routers, etc.. Since it also uses both analogue and digital leased lines, its reach is greater. It can connect any location in the world, irrespective of its distance and/or remoteness. 10. Since analogue trunk cards are used as standard in the VDPS, where analogue lines are available, these are directly terminated on these trunk cards.

In the PVDTN system of 176287, the data connectivity is through switched universal channels which are suitable for either voice, or fax, or data corrmunicat ion, alternately, with automatic switching between the different modes of corrmunicat i on through the VDPS. Where the volume or frequency of data corrmunicat ions is high, such as the railway reservation system, the airline ticketing system, banks for ATM networks, etc, such universal switched connections may not always be conducive to eficient functioning. For such applications, continuous non- switched data connections between LAN buses at either end of the line may be desired.

In the present invention an arrangement has, therefore, been made to by-pass the VDPS at each location and terminate a line directly on the WAN (wide area network) ports of data routers sitting on the LAN (local area network) buses at either end of the line. This can be done by segregating a part of the bandwidth of a digital 64 KBPS line, in the fixed channel ADPCM multiplexer through a data I/O ( i nput /output ) card, and terminating this on the data router WAN port, by-passing the VDPS at either end; or through a separate analogue leased line terminating on the WAN ports of the data routers at both ends of the line, by-passing the VDPS at either end, where digital leased lines are not available. The arrangement is shown in Fig. .

Because of this feature the system can now provide the flexibility of the universal switched data connectivity, for normal data corrmunicat ions volumes and frequencies, and fixed non-switched data pipe connectivity for high vol ume s or frequencies of data corrmun icat ions .

In the PVDTN system of 176287, digital extensions can have data connectivity with same type of extensions within the domain of the same VDPS. Also analogue and long line analogue extensions can have data connectivity with similar extensions. The present sy s tem does not provide for analogue or long line analogue extensions to have data connectivity with digital extensions in the same VDPS domain. When the system of Patent 176287 was conceived, this was not important, as the comparatively slower speeds of dial-up modems precluded the use of analogue or long line analogue extensions or LAN application. For LAN application, only digital extensions were contemplated. The higher modem speeds and the lower costs of such modems, now available, make analogue extension usage in LANs a distinct possibility, hence interconnection between digital and both types of analogue extensions for data assumes prime importance.

A trunk loop back system, has, therefore, been used, which will make this desired data connectivity between analogue and digital extensions of the same VDPS, possible. This is shown in Fig.3. This arrangement will give the following benefits to the PVDTN system of 176287. (i) It will facilitate use of analogue and long line analogue extensions of the VDPSs in making up the LAN with the help of the low cost high speed dial-up modems now available. (ii) The more costly digital extensions will be used for larger distances where the cost of cabling justifies the use of a single shielded twisted pair cable and voice-data telephone for simultaneous voice/data connect- ivity in the LAN.

(iii) This new innovation will, therefore, reduce the cost of LAN build up in the syst em o f

176287, and facilitate peer to peer computer connectivity between analogue and digital extensions of the same VDPS.

Larger organizations/companies have many locations in the same city or town. If there is a private network, then these locations need to be included in the network, through a metropolitan area network, with voice/ fax/data connectivity. For such connections currently there are two options.

1. A digital leased line with voice-data multiplexers, data routers, etc, connecting the additional locations to the main network of the city as is done for voice over data private networks ( VODPNs ) .

2. Auxiliary VDPSs situated at the additional locations connected to the main VDPS in the city/town through analogue or digital lines, or alternatively, individual non-exchange leased lines connecting telephones, fax machines, and computers through dial- up modems to the long-line extensions of the central VDPS in each city or town up-to a distance of about 15 Kms . In the latter system, there could be a breach of security as the long line extensions move through the Main Distribution Frames (MDFs ) of various exchanges and could be tapped with the help of unscrupulous PTT staff.

Both the above options are cost intensive, particularly the fist, making the voice data metropolitan area network VDMAN configurations non-viable.

To provide a cost effective voice/ fax/data metropolitan area connectivity, a system has, therefore, been incorporated comprising of long line analogue extensions, analogue subscriber carrier system (ASCS), and non-exchange leased lines or private wire, as shown in Fig.4 which provides the following benefits to the patented private voice data telecorrmunications network system of 176287, and in combination with the latter produces a VDMAN solution which is much lower in cost than the voice over data private network (VODPN) system referred to in option 1 above.

The new VDMAN solution will provide the following benef its. (i) A single non-exchange line hired from the PTT facilitates up-to eight long line extensions of the central VDPS in each city/town to be connected to telephones, fax machines, and computers through dial-up modems, at the remote location of the Company /Organ i zat i on in the same city/town, through the analogue subscriber system (ASCS). The telephones, fax machines, and computers situated in the remote location have simultaneous access to the VDPS at the central location and through it to the rest of the network. (ii) Since the ASCS puts the signals of the eight long line extensions through a common carrier tapping of the non-exchange leased line through normal methods will not help the tapper to listen to or obtain anything other than carrier noise. This ensures and preserves the 100% security of the network, (iii) Since one non-exchange line takes care of eight long line extensions at the remote end, the cost of setting up the network and opera- ting it is considerably lower than what would be incurred in the system of 176287, and substantially lower than the connectivity through the voice over data private network (VODPN) system. (iv) This new arrangement, therefore, reduces the cost of metropolitan area network build-up for integrated voice/fax/data networks, and provides much greater flexibility in total network design.

in the PVDTN system of 176287, since the data connection is through serial ports, the maximum number of simultaneous access to a local host or server computer from any other computer in the network, was limited to the number of serial ports available in the host or server, and since these were limited to a maximum of eight (in Unix machines) or even less in the modern servers/hosts, the number of simultaneous multiple access to these machines from other computers in the network were limited. However, with INTRANET type operations, and ERP (enterprise resource planning) applications now emerging, multiple simultaneous access to local hosts/ servers from any computer in the network has become essent ial .

In view of this requirement, multiple simultaneous connectivity to local hosts/ server s from computers in the network is now provided through line terminal servers (LTS) whose serial ports will be connected to the VDPS of the PVDTN network through analogue extensions and dial-up modems, or digital extensions and voice-data telephones with digital terminal interfaces (VDTs) and which will be connected to the HOST/ server through the Ethernet/DEC net LAN buses. If more simultaneous accesses are required, a second or more LTSs is/are connected between the LAN buses and the VDPS of the location in the manner described above.

This arrangement facilitates multiple simultaneous access to the Host/Server at each city/town from any computer in the VDLAN/VDMAN across the voice data wide area network VDWAN.

The inventive feature described herein and the Figs.l to 5 of the accompanying drawings therefore bring about substantial improvements over the present art of voice over data private networks over digital leased lines (VODPN), and private voice-data telecom network system (PVDTN) of Indian Patent 176287, and provide major economic benefits and technical advantages to the prospective network users, over the currently known systems of the integrated voice and data private networks.

Claims

CLAIM:

1. An improved, private combined, voice, fax, and data tel ecorrmunicat ion network, PVDTN system suitable for performing voice, fax and data corrmun icat ions between an organization's locations spread over a city, country, and the world over a network of analogue, digital, a mixture of analogue and digital terrestrial leased or owned lines, non-exchange leased lines or private wire, and point-to-point satellite links, comprising: transmission media between all major locations of the network and between major and minor locations in the i r regions ; voice data private switches comprising (ISDN) internal digital services network compatable EPAXs analogue with they digital and long line analogue extension cards, modem pooling cards and voice data telephones with digital terminal interfaces; leased line modems for analogue leased or owned lines, dial up modems for analogue and long line analogue extens ions ; appropriate media, cables, etc., for local area connectivity for individual corrmunicat ing devices to the VDPSs at each location; and appropriate software and the circuit switched connection for peer to peer data corrmunicat ion between computers connected to the network without involving HOST/ SERVER computers in any way; characterised in that a corrmon trunk arrangement of analogue 2W or 4W, E&M trunk circuits of the VDPS is provided, which terminate on multiple vocoders of the ADPCM fixed channel multiplexers, the aggregate of which is terminated on the digital leased lines of 64 KBPS or higher band-widths, and directly on to 2W or 4W, E&M, analogue leased lines; a VDPS by-pass arrangement is used for providing fixed data pipes for direct and continuous LAN to LAN data link across the VDMANs/VDWAN (voice-data wide area network) without switching, by using a dedicated part of the bandwidth of a 64 KBPS leased line or a separate analogue 1-eased line, which ever is available between the two connected locations; a trunk loop back arrangement is in corporated for 0 providing data connectivity between digital extensions of a VDPS with the analogue or long line analogue extensions of the same VDPS, facilitating peer to peer data corrmunicat ions between two computers connected to digital and analogue extensions within 5 the same VDPS domain, without involving the Host or Server in the location; a cost effective and 100% secure VDMAN connectivity solution is adopted using long line extensions of the VDPS, analogue subscriber carrier system (ABCS), 0 ^ar>d non-exchange leased lines or private wire, which facilitates simultaneous voice, fax, and data connections to telephones, fax machines and computers located at various organization locations in a town or city; and 5 a system for multiple access to a local server/host computer through the PVDTN from computers in the VDLAN/VDMAN/ across the VDWAN, using one or more line terminal servers connected to the VDPS through analogue and digital extension of the VDPS through

30 their serial ports, and to the HOST/SERVER through the Ethernet LAN bus.

2. The system as claimed in claim 1, wherein a virtual circuit is established between two corrmun i cat ing devices located anywhere in the network, through

^^ dialing of specific numbers of these devices, facilitating unhindered and 100% secure corrmunicat ions between any two telephones, any two fax machines, and any two computers, connected to the network during the circuit switched connection.

3. The system as claimed in claim 1 and 2, wherein any two computers in the network can communicate with each other directly, without involving the Host/ Server computer, with each other irrespective of the platforms in which they are operating, facilita- ting direct corrmunicat ions between two terminals, two work stations, two servers, server to client, client to server, through establishment of virtual circuits between the corrmun i cat ing computers either directly or through auto-rerouting.

4. The system as claimed in claim 1, wherein several telephones located at different parts of the network can conrmunicate with each other simultaneously with all of them listening to the conversation between each other using the conference facility of the EPAXs to which they are connected, in the form of multi- locational voice conference.

5. The system as claimed in claim 1 and claim 4, wherein along with the voice conference set up between several telephones, the adjoining computers can 5 all log on to a common data base through the multiple access facility associated with each server or host computer, for a voice-data conference.

6. The system as claimed in claim 1, wherein the direct in-line dialing capability of the VDPSs through Q a closed numbering system, can facilitate direct connection between any two similar corrmun i cat ing devices like two telephones, two fax machines, and two computers, either directly or through automatic re-routing, and without any operator interface. 5

7. The system as claimed in claim 1, wherein through a monitoring console of the VDPS, the operator or any designated person at each organization location, can monitor and ascertain the people using the network at any point of time and intervene to clear any hold ups, should an emergency call be required at that point of time.

8. The system as claimed in claim 1, wherein the VDPSs in the network have the switching and switch routing intelligence for the local area, metropolitan area, and wide area networks of the system.

9. The system as claimed in claim 1, wherein the ASCSs connect the telephones, fax machines, and computers located in other offices in the s ame city to the long-line exchanges of the central VDPS of the city for simu ltaneous corrmunications to other extensions of this VDPS and through it automatically to any other telephone, fax machine, and computer in the network.

10. An improved, 100% secure, cost effective, private integrated voice, fax and data telecorrmunicat ions system over a network of analogue, digital, and a mixture of analogue and digital terrestrial leased lines, non-exchange leased lines or private wire, and point-to-point satellite links, substantially as herein described with reference to Figs.l and 2 to 5 of the accompanying drawings.