COMMUNICATION SYSTEM

Abstract: An interface and method for connecting a remote key telephone set (KTS) to a private branch exchange (PBX) through a public switch telephone network (PSTN), so that the KTS operates as part of the PBX, and a communication system including a private branch exchange (PBX), a public switch telephone network (PSTN), a remote workplace including a workstation, a remote key telephone set (KTS), and an interface between the public switch telephone network and the remote key telephone set, and a KTS server coupled to the remote workstation over the public switch telephone network, and coupled to the PBX, to enable the remote KTS to function as part of the PBX.

Description: COMMUNICATION SYSTEM FIELD OF THE INVENTION The present invention relates to a communication system for a home office and, in particular, to a home office communication system which makes a key telephone set in the home a part of the workplace PBX, and a workstation in the home part of the workplace LAN. BACKGROUND OF THE INVENTION There are known a number of private branch exchanges (PBX), internal telephone systems for a business or workplace, including a number of smart phones, or key telephone sets. These key telephone sets are programmed to provide services in addition to the traditional transfer of voice messages, including providing a number of internal phone lines, indicating by means of LED's which lines are in use, conference calls, putting calls on hold, and so on. Two separate types of channels typically are required to connect a PBX and each key telephone set or other "smart" interface, one for control signals, generally known as a D channel, and another type for voice, known as B channels. However, these PBX systems are limited to key telephone sets located in the organization workplace. Recently so-called Computer Telephony Integration (CTI) systems have been developed which attempt to integrate the operation of telephones and computers. An Ethernet card, or other LAN gateway, is added to the switch to provide a gateway or interface from the PBX to an organization LAN in the organization workplace. With the increasing developments in computer and facsimile technology, many people are now working in a home office, rather than sitting physically at their workplace. Accordingly, it would be very desirable to have a seamless communications system for a home office which permits transfer of both voice and data over public telephone lines, so as to connect the home office to the workplace. There have also been great strides made in utilizing the Internet from home computers. One of the newer innovations is Voice over Internet Protocol (VoIP) technology, wherein voice signals can be transmitted over the Internet connection telephone line. SUMMARY OF THE INVENTION According to the present invention, there is provided a communication system including a private branch exchange (PBX), a public switch telephone network (PSTN), a remote workplace including a workstation;- a remote key telephone set (KTS); an interface between the public switch telephone network and the remote key telephone set; and a KTS server coupled to the remote workstation over the public switch telephone network, and coupled to the PBX, to allow the remote KTS to function as part of the PBX. According to the invention, there is also provided an interface for connecting a remote key telephone set (KTS) to a private branch exchange (PBX) through a public switch telephone network (PSTN), so that the KTS operates as part of the PBX. According to the invention, there is further provided a method of connecting a remote key telephone set to a private branch exchange (PBX) including the steps of: coupling a remote key telephone set (KTS) to a remote workstation; coupling the remote workstation to a KTS server via a public switch telephone network (PSTN) and coupling the KTS server and the PBX for exchange of control signals; and coupling the workstation and the PBX via the public switch telephone network for exchange of voice information. There is further provided in accordance with the present invention a method of exchanging information between a private branch exchange (PBX) and a remote key telephone set (KTS) including the steps of: establishing a LAN protocol stack link between a remote workstation coupled to the KTS and a KTS server coupled to the PBX via public switch telephone network; establishing a virtual link over the LAN protocol stack link between the remote workstation and the KTS server which is equivalent to physically connecting the KTS and the PBX; exchanging control signals over the virtual link; and exchanging voice between the KTS and the PBX over the public switch telephone network. There is also provided in accordance with the present invention, a method of connecting a remote key telephone set to a private branch exchange (PBX) including the step of coupling an interface between the remote key telephone set (KTS) and a private branch exchange (PBX) through a public switch telephone network (PSTN), so that the KTS operates as part of the PBX. BRIEF DESCRIPTION OF THE DRAWINGS The present invention will be further understood and appreciated from the following detailed description taken in conjunction with the drawings in which: Fig. 1 is a schematic illustration of a communication system constructed and operative in accordance with one embodiment of the invention; Fig. 2 is a schematic illustration of a PC card according to one embodiment of the invention; Fig. 3 is a flow chart of the operation of the client workplace KTS according to one embodiment of the invention; Fig. 4 is a flow chart of the link establishing process in the KTS server; Fig. 5 is a flow chart of the operation of the KTS server according to one embodiment of the invention; Fig. 6 is a schematic illustration of a communication system constructed and operative in accordance with an alternative embodiment of the invention; Fig. 7 is a schematic illustration of a PC card according to one embodiment of the invention for use in the communication system of Fig. 6; Fig. 8 is a schematic illustration of a PC card according to another embodiment of the invention for use in the communication system of Fig. 6; and Fig. 9 is a schematic illustration of a communication system constructed and operative in accordance with an alternative embodiment of the invention. DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a communication system which permits coupling of a Key Telephone Set (KTS) at a remote client workplace to the private branch exchange (PBX) of an organization workplace, to provide a full featured KTS over the Public Switch Telephone Network (PSTN). According to one embodiment, the invention permits coupling of a client workstation at the location remote from the organization workplace to connect with the workplace Local Area Network (LAN) over the PSTN for data transfer, and permits coupling of a Key Telephone Set (KTS) connected to the client workstation at the remote client workplace to the private branch exchange (PBX) of the organization workplace, to provide a full featured KTS over the PSTN. This is accomplished by connecting the KTS or the client workstation to the PBX via a KTS server. For purposes of the present application, the LAN connection and link establishment uses a TCP/IP protocol stack, since today it is the most popular means of connection. However, alternatively any other LAN and WAN (Wide Area Network) protocol stack can be utilized. Referring now to Fig. 1, there is shown a schematic illustration of a communication system constructed and operative in accordance with one embodiment of the invention and including an organization LAN 10 with an associated private branch exchange (PBX) 12. PBX 12 is coupled to LAN 10 via a LAN gateway (not shown), such as a conventional Ethernet card, and includes ISDN interfaces 38 (PRI and/or BRI) for connection to the public telephone network (PSTN) 30. The LAN gateway is preferably a PC card, which serves as the PBX gateway to the Ethernet/TCP/IP organization's LAN. While ISDN connections are preferred, it will be appreciated that any other suitable connection can be utilized, including any PSTN lines. LAN 10 includes a network server 16 and a plurality of organization workstations 18 and so forth, as known. The workplace also includes a plurality of key telephone sets (not shown) coupled to PBX 12. There can also be a plurality of POTS (Plain Old Telephone Set) coupled to PBX 12. It will be appreciated that none of these telephone sets need be connected to LAN 10 in the workplace. A client workplace 20 is located at a remote location, such as the client's home. Client workplace 20 includes a workstation 22, which is preferably a personal computer, such as IBM PC, MAC, Sun Workstation, and so forth, and a key telephone set (KTS) 24. It will be appreciated that KTS 24 can be identical to those key telephone sets in the organization workplace. A cable 26 from KTS 24 is plugged into a KTS interface 50 in workstation 22, as described in detail below, instead of into a telephone plug in the wall. According to the illustrated embodiment of the present invention, the client workplace is coupled to the organization LAN and PBX over the public telephone network (PSTN) 30 via ISDN lines 32,34 and a KTS server 36. KTS server 36 is a server computer connected to the organization LAN 10. It is a particular feature of this server that its architecture and its hardware, including ISDN interfaces for PRI and BRI lines, are similar to the architecture in the servers of conventional Internet Service Providers (ISP). In addition, a software application is provided to permit it to function as a server for a remote KTS, as described below. The organization PBX 12 is coupled to the PSTN 30 by ISDN line 38. Workstation 22 is coupled to the PSTN 30 by BRI line 32. In the embodiment illustrated in Fig. 1, the client workstation 22 includes an interface card for interfacing with PSTN 30 and with KTS 24. One example of a suitable interface card, in the form of a PC card, is shown in Fig. 2. PC card 40 includes a BRI (Basic Rate ISDN) interface 42, for coupling the workstation via BRI 32 to PSTN 30, a KTS interface 50, for coupling to KTS 24, and an interface 60 to the workstation 22 bus (e.g., ISA/EISA) to allow control of the BRI and KTS interfaces. BRI interface 42 is like a standard BRI interface card in relation to the PSTN and the operating system, permitting use of two B channels 44, 46, and one D channel 48. With this card, the user can connect, for example, to his Internet service provider and connect to the Internet from his private workstation. From the KTS perspective, the card is the interface to send and receive messages to PBX 12. While, for ease of discussion, the invention is described herein with regard to ISDN (BRI or PRI) lines, it will be appreciated that alternatively any other similar form of Public Switched Telephone Network (PSTN) line can be used, including at least two regular analog trunks, or any other communication lines to be developed in the future. All these are considered to be within the scope of the invention. Where line 32 consists of two regular analog lines, the interface 42 will be an analog modem card that supports two analog line interfaces to PSTN 30. Similarly, ISDN line 34 can be a plurality of analog lines, instead of ISDN lines. KTS interface 50 includes two B channels 52, 54, and one D channel 56. The D channel 56 of KTS interface 50 is coupled to B channel 46 of BRI interface 42 to permit passage of control messages from KTS 24 over PSTN 30 via one B channel 46 of BRI interface 42. One B channel 52 of KTS interface 50 is coupled to B channel 44 of BRI interface 42 to permit passage of voice information from KTS 24 over PSTN 30 via the other B channel 44 of BRI interface 42. It will be appreciated that, in this configuration, the second B channel 54, which is a voice channel, cannot be used. Client workstation 22 runs application software, which is able to read and write to the channels in the KTS and the BRI interfaces, and also to switch between their B channels. In general, operation of the communication system is as follows. The KTS control messages (the KTS's D channel messages) are passed over the public network PSTN 30, as TCP/IP messages, via one of the B channels of the BRI line, and the second B channel is used to convey voice. The first B channel from the client workstation (the channel which will pass the control messages) is connected to the KTS server 36 in the same way that home Internet users connect to their Internet service providers. The control messages will then arrive at PBX 12 as TCP/IP messages via the LAN gateway. Referring now to Fig. 3, there is shown a flow chart of the operation of the client workstation KTS software. When a Link Establish screen is displayed (block 62), the user starts establishing the remote station connection. He requests to establish the link (block 64) and the application running in the client workstation runs the establish link process (block 66). (Alternatively, the user can establish the link by running his regular software connection to the Internet, but instead of dialing the phone number of his Internet service provider, he dials the phone number of KTS server 36, and types his username and password.) Server 36 has a protocol stack and operates like the Internet service provider's server to provide protocol conversion, as needed. Thus, the remote computer actually becomes a computer in the organization LAN 10, with all the data capabilities of a local computer 18 (block 66). The Remote KTS-Client will open a session with the KTS-Server application over the TCP/IP channel that has been established, in order to establish a Virtual Link with the PBX (block 68). The connection established between the sides is functionally equivalent to physically connecting the KTS and the PBX, i.e., connecting the KTS cable to the wall in the organization workplace. The KTS server 36 reports to PBX 12 the establishment of a new active remote station. PBX 12 registers this fact in the database. When the remote station finishes the login process to the server, it is in its steady state. The steady state has the following characteristics: 1. One B channel at client workstation 22 is used for a TCP/IP connection with the organization KTS server 36. Client workstation 22 is actually a station in the organization LAN 10 for all data purposes. 2. Over the same B channel, a special virtual link over a TCP/IP connection exists between the client workstation 22 and the server 36. This virtual link will carry the control messages to KTS 24 over the public network PSTN 30 to PBX 12 and back. 3. The second B channel in the remote workstation is ready to accept voice calls from PBX 12. When a setup message arrives from PBX 12, this channel is switched to one of the KTS B channels to establish a voice call. Client workstation 22 now awaits receipt of messages, either from KTS server 36 or from KTS 24 (block 70). If treatment is necessary (block 72), workstation 22 processes the message (block 74). The message is then sent to its destination (block 76). The KTS server 36 has the following functionality: 1. Establishing a TCP/IP connection via the LAN gateway for passing messages with PBX 12. 2. Accepting requests from any remote workstations to connect to the TCP/IP organization LAN over ISDN lines. 3. Accepting requests from remote KTS-Client applications to the remote KTS-Server application to establish virtual links over the public network PSTN 30 for passing control messages to and from the remote KTS 24. 4. Passing messages over the virtual links described in paragraph 3 between PBX 12 and the remote key telephone sets 24. In other words, KTS server 36 serves as an interface to the organization LAN 10 for data purposes, and as distributor/concentrator of control messages to and from a plurality of client workplaces 20 to the PBX. Operation of the KTS-Server 36 will now be described with reference to Figs. 4 and 5. Fig. 4 is a flow chart of the KTS server Link Establishment process. Remote KTS-Server 36 initializes the ISP protocol stack package (block 80), establishes a TCP/IP connection with PBX 12 (block 82), and awaits receipt of a request to establish a TCP/IP link from client workstation 22 (block 84). When a request is received, server 36 establishes the link and updates the relevant data structure (block 86). The Remote KTS-server application is now ready to accept requests to establish a virtual link with the remote KTS-client application, as set forth in the flow chart in Fig. 5. The application's data structure is initialized (block 90), and the server waits (block 92) for to receive a message from a remote workstation, a remote key telephone set or the PBX. If a request to establish a Virtual Link is received from a remote workstation (block 94), the KTS server validates the user name and password of the remote user, sends to the PBX a message that a virtual link has been established, and sends an acknowledgement message to the client workstation (block 96). If a signaling message is received from a remote key telephone set, which is already logged in, to be sent to the PBX (block 98), the KTS server reads the message, processes it, if necessary, and sends it to the PBX (block 100). If a signaling message is received from the PBX for a remote key telephone set which is logged in (block 102), the KTS server reads the message, processes it, if necessary, and sends it to the appropriate key telephone set (block 104). In PBX 12, a new internal KTS port type is defined, and a new driver provided for this port. The driver is a combination of KTS and ISDN drivers. The new driver sends all the remote KTS control messages through the LAN gateway, and establishes voice calls with the remote KTS 24, using an ISDN port through a peripheral cards controller. The signals are routed through LAN 10 to KTS server 36 and, from there, over the ISDN line 38 to client workstation 20. An example of the message flow in the communication system according to the embodiment of Fig. 1 will now be described with relation to the situation where the user at a client workplace 20 has taken the KTS 24 receiver off the hook. The remote KTS-Client application will get an offhook message from KTS 24, and the application will send it as a TCP/IP message across the public network 30 to PBX 12 through the KTS server. The KTS driver in PBX 12 will get this message, and will send back, along the same route, messages to turn on the Speaker LED and update the display in KTS 24. Then, the driver will choose an ISDN port and through the peripheral cards controller will send to PSTN 30 a setup message to establish a call with the second B channel at the far extension. PBX 12 will then send a DialTone to the ISDN port. It will be appreciated that, alternatively, PBX 12 can be connected directly, by a point-to-point connection, to KTS server 36 for voice only connection. In this case, the PBX 12 need not be connected to the organization LAN, and the remote workstation will have only voice capabilities, and will not have the capability of data connection to the organization LAN. Referring now to Fig. 6, there is shown a schematic illustration of a communication system constructed and operative in accordance with an alternative embodiment of the invention. This embodiment is substantially similar to that in Fig. 1, except with regard to implementation of the voice passing portion. Like elements have like reference numerals. According to the embodiment of Fig. 6, Voice over IP (VoIP) technology is utilized for voice transfer. As can be seen, an organization LAN 10 is coupled to an associated private branch exchange (PBX) 12 via a LAN gateway. LAN 10 includes a network server 16 and a plurality of organization workstations 18, each including an associated key telephone (not shown) coupled to PBX 12, all as described above. A client workplace 20 is located at a remote location, such as the client's home. Client workplace 20 includes a workstation 22 and a remote key telephone set (KTS) 24. KTS 24 may be any key telephone, or the same key telephone in use in the organization workplace. A KTS interface 26 couples KTS 24 with workstation 22. In this embodiment, the client workstation is coupled to the organization LAN and PBX over the public telephony network (PSTN) 30 via ISDN lines 32, 34, and a KTS server 36, as described above. In the embodiment illustrated in Fig. 6, the organization PBX 12 is not coupled directly to PSTN 30 for purposes of transmitting voice, and this connection, therefore, is not shown in Fig. 6, although it remains for other conventional purposes. Rather, for purposes of voice transmission, PBX 12 is coupled by line 38' to KTS server 36, which is connected to PSTN 30 by ISDN line 34. The same 64 Kbps (B channel) used for the TCP/IP data and control signaling will now be used also to pass voice. Workstation 22 is coupled to the PSTN 30 by BRI line 32. Client workstation 22 includes an interface card for interfacing with BRI 32 and with KTS 24. One example of a suitable interface card for the communication system of Fig. 6, in the form of a PC card, is shown in Fig. 7. PC card 1 10 includes a BRI interface 1 12, for coupling BRI 32 to PSTN 30, a KTS interface 120, for coupling to KTS 24, and an interface 130 to the workstation 22 bus (e.g., ISA/EISA) to allow control of the BRI and KTS interfaces. BRI interface 1 12 is similar to BRI interface 42 of Fig. 2, permitting use of two B channels 116, 118, and one D channel 114. However, in this configuration, workstation 22 is connected to the KTS server 36 using one B channel 1 18 in BRI interface 1 12. KTS interface 120 includes two B channels 122, 124, and one D channel 126. The B channel 118 of BRI interface 112 is coupled to D channel 126, B channel 122, and B channel 124 of KTS interface 120 to permit passage of control messages, as well as voice. This means connecting at a rate of 64 Kbps, which enables the use of the two voice B channels in the KTS interface 120 (8 Kbps for each B channel). The rest of the bandwidth is available for control messages and for data transfer. It will be appreciated that, when the KTS is idle, only D channel 126 is utilized, when one voice connection is desired, D channel 126 and one B channel 122 are utilized, and if two simultaneous voice connections are desired, both B channels 122 and 124 can be utilized. According to an alternative embodiment, shown in Fig. 8, both B channels 1 16' and 1 18' are connected to KTS server 36 and to the two B and one D channels of KTS interface 120. This means connecting at a rate of 128 Kbps, and enabling the use of both voice channels 122 and 124 in KTS interface 120 (8 Kbps per B channel). The rest of the bandwidth, which is now much larger, is available for control messages and for data transfer. Preferably, the client workstation can select which option, 64 Kbps or 128 Kbps (the configuration of Fig. 7 or Fig. 8) that he wishes to use. According to an alternative embodiment of the invention, the interface card and client workstation could be combined as a separate unit, or the functions thereof could be combined into the remote KTS, thereby eliminating the need for a separate client workstation. Referring now to Fig. 9, there is shown a schematic illustration of a communication system constructed and operative in accordance with another alternative embodiment of the invention. This embodiment is substantially similar to that in Fig. 1, except with regard to the client workplace. Like elements have like reference numerals. According to the embodiment of Fig. 9, the client workplace 20' does not include a workstation, but merely a remote key telephone set 24. KTS 24 may be any key telephone, or the same key telephone in use in the organization workplace. In this embodiment, the KTS interface 26' couples KTS 24 to the organization LAN and PBX over the public telephony network (PSTN) 30 via ISDN lines 32, 34, 38, and a KTS server 36, for transmission of voice and KTS control messages. It will be appreciated that a client workplace without a workstation can also be utilized in the embodiment of Fig. 6. It will be appreciated that the invention is not limited to what has been described hereinabove merely by way of example. Rather, the invention is limited solely by the claims which follow.

Claims: CLAIMS 1. A communication system comprising: a private branch exchange (PBX); a public switch telephone network (PSTN); a remote workplace including: a workstation; a remote key telephone set (KTS); and an interface between said public switch telephone network and said remote key telephone set; and a KTS server coupled to said remote workstation over said public switch telephone network, and coupled to said PBX, to enable said remote KTS to function as part of said PBX. 2. The communication system according to claim 1, further comprising an organization LAN, and wherein said PBX is coupled to said organization LAN; and said KTS server is coupled to said organization LAN. 3. The communication system of either claim 1 or claim 2, further comprising, a coupling for voice between said public switch telephone system and said private branch exchange. 4. The communication system of either claim 1 or claim 2, further comprising a coupling for voice between said KTS server with said private branch exchange. 5. The communication system of any of claims 1 to 4, wherein said interface includes: a PSTN line interface; a KTS interface; and an interface to a workstation bus to allow control of said PSTN line interface and said KTS interface. 6. The communication system of claim 5, wherein said PSTN line interface includes a Basic Rate ISDN (BRI) interface to allow control of said PSTN line interface. 7. A communication system comprising: an organization LAN; a private branch exchange (PBX) coupled to said organization LAN; a public switch telephone network (PSTN); a remote workplace including: a workstation; a remote key telephone set (KTS); and an interface between said PSTN and said remote key telephone set including: a PSTN line interface; a KTS interface; and an interface to a workstation bus to allow control of said PSTN line interface and said KTS interface; a KTS server coupled to said organization LAN, to said PBX, and via ISDN lines to said public switch telephone network; and ISDN lines coupling said workstation with said KTS server over said public switch telephone network, to enable said remote KTS to function as part of said PBX. 8. The communication system of claim 7, further comprising an additional ISDN line, for voice, coupling said public switch telephone network with said private branch exchange. 9. The communication system of claim 7, further comprising an additional ISDN line, for voice, coupling said KTS server with said private branch exchange. 10. The communication system according to any of claims 7-9, further comprising a driver in said PBX, said driver being a combination of KTS and ISDN drivers. 1 1. An interface for connecting a remote key telephone set (KTS) to a private branch exchange (PBX) through a public switch telephone network (PSTN), so that the KTS operates as part of the PBX. 12. The interface according to claim 1 1, wherein said PSTN line is an ISDN line. 13. A method of connecting a remote key telephone set to a private branch exchange (PBX) comprising the steps of: coupling a remote key telephone set (KTS) to a remote workstation; coupling said remote workstation to a KTS server via a public switch telephone network (PSTN) and coupling said KTS server and said PBX for exchange of control signals; and coupling said workstation and said PBX via said public switch telephone network for exchange of voice information; whereby said remote KTS functions as part of said PBX. 14. The method according to claim 13, wherein said step of coupling said workstation and said PBX includes coupling said workstation to said PSTN, and coupling said PBX to said PSTN. 15. The method according to claim 13, wherein said step of coupling said workstation and said PBX includes coupling said workstation to said PSTN, coupling said PBX to said KTS server, and coupling said KTS server to said PSTN. 16. The method of any of claims 13 to 15, and further comprising the steps of: coupling said remote workstation to said KTS server via said PSTN; and coupling said KTS server to an organization Local Area Network (LAN) for exchanging data between said workstation and said LAN. 17. The method of exchanging information between a private branch exchange (PBX) and a remote key telephone set (KTS) comprising the steps of: establishing a LAN protocol stack link between a remote workstation coupled to the KTS and a KTS server coupled to the PBX via public switch telephone network; establishing a virtual link over said LAN protocol stack link between said remote workstation and said KTS server which is equivalent to physically connecting the KTS and the PBX; exchanging control signals over said virtual link; and exchanging voice between the KTS and the PBX over said public switch telephone network. 18. The method according to claim 17, further comprising the steps of: coupling said KTS server to an organization Local Area Network (LAN) for exchange of data; and exchanging data between said LAN and said remote workstation via said KTS server over said LAN protocol stack link. 19. The method according to either of claims 17 and 18, wherein said step of establishing a LAN protocol stack link including establishing a TCP/IP link. 20. A method of connecting a remote key telephone set to a private branch exchange (PBX) comprising the step of coupling an interface between said remote key telephone set (KTS) and a private branch exchange (PBX) through a public switch telephone network (PSTN), so that said KTS operates as part of said PBX.

Inventors: NEUMAN AHARON, NEUMAN, AHARON
Applicants: ECI TELECOM LTD, NEUMAN AHARON, ECI TELECOM LTD., NEUMAN, AHARON
Application year: 1999
Main classification: H04Q11
IPC codes: H04M3, H04M7, H04M9, H04Q3