Abstract: Cache memory clock generation circuits for reducing power consumption and read errors in cache memory are provided. In one aspect, a cache memory clock generation circuit employs detector circuit configured to receive a way address and generate a one way hit signal indicating if cache read request results in a single way hit. Clock and enable circuit is configured to generate a cache clock signal in response to a system clock signal and a cache enable signal, and generate a cache read enable signal in response to the cache clock signal and a read enable signal. Gating circuit is configured to generate a read clock signal in response to one way hit signal, cache clock signal, and cache read enable signal. Sense amplifier clock generation circuit is configured to generate sense amplifier clock signal in response to the read clock signal having a defined pulse width.

Abstract: A system and method for providing PBX-like functionality at a mobile location includes the capability of maintaining a network session with a mobile number associated with a remote worker. The system utilizes a remote office platform interposed between a data communications network and a conventional PBX switch. A remotely located individual (such as a telecommuter) “logs in” to the remote office platform and, once the individual is authenticated, PBX-like communication with the mobile device is established. If the device is a computer-enabled device and includes a display, the platform can enable a graphical user interface emulating a PBX station set to the device. Alternatively, the remote worker can enter either spoken commands or series of DTMF sequences to utilize the PBX-like features. For these applications, the remote office platform includes a speech recognition module and a translation table for converting a sequence of DTMF tones into a PBX-like call feature (e.g., transfer, hold, mute, etc.).

Abstract: In one embodiment, method can include: receiving an address in a call agent, the address being associated with a call; triggering a trunk group selection algorithm in response to at least a portion of the received address, the trunk group selection algorithm providing a selection result from among a trunk group placeholder and a plurality of trunk groups; and forwarding the call to a trunk group determined by a caller-associated attribute when the selection result comprises the trunk group placeholder.

Abstract: Embodiments of the invention include a method for routing an Internet Protocol (IP)-based call through a first IP-based network to a second IP-based network. The method includes receiving an IP-based call request in the first network; identifying one or more geographic trunk groups that can be used to route the call request out of the first network, wherein each of the one or more geographic trunk groups represents a logical grouping of one or more IP trunk groups between the first IP-based network and the second IP-based network; selecting one of the one or more geographic trunk groups; and routing the received call request via the selected geographic trunk group to an IP address associated with the selected geographic trunk group. Other embodiments are also disclosed.

Abstract: In one embodiment, method can include: receiving an address in a call agent, the address being associated with a call; triggering a trunk group selection algorithm in response to at least a portion of the received address, the trunk group selection algorithm providing a selection result from among a trunk group placeholder and a plurality of trunk groups; and forwarding the call to a trunk group determined by a caller-associated attribute when the selection result comprises the trunk group placeholder.

Abstract: A method is disclosed that provides the sharing of a station-mapping description with a first private-branch exchange, where the description has been initialized and maintained at a second private-branch exchange. Such a description describes a logical association between a station extension of an enterprise deskset and a telephone number of an off-premises terminal, such as a cell phone. As a result of the sharing across private-branch exchanges, an incoming call from a second employee's cell phone can be recognized, by a first employee being called, as coming from the calling second employee. This is because the incoming call is identified with the telephone extension of the calling employee's deskset terminal in spite of the call being placed from the cell phone, or other telephone number at large. This is particularly important where a large company engineers its enterprise's telecommunications system across multiple private-branch exchanges.

Abstract: A query message-based call routing mechanism for a limited access cooperative telecommunication network initially determines whether the called party is commonly located at the same node as the calling party. If not, the calling party node broadcasts a query message to all other nodes in the network to locate the called party. Only the node having local knowledge of the called extension will reply to the query message. Once the node sourcing the query message has received this reply message, it will place a call to the node servicing the called extension.

Abstract: A method for setting up a communication connection between a calling communication terminal and another communication terminal belonging to a group in a communication network selected by the calling party dialing an allocated group telephone number, the other communication terminal being selected by an exchange unit of the selected communication network by means of availability information, and the connection initiated through the exchange of a start message and a number of connection confirmation messages between the calling communication terminal and the selected other communication terminal. A private branch exchange with a server which comprises an exchange unit and to which a plurality of communication terminals combined in groups is connected, carries out the method.

Abstract: According to one embodiment, a telephone system which realizes voice communication by using a packet network comprises an exchange which accommodates a telephone terminal as its extension and a call processing server which processes calls on the packet network. The exchange comprises a first trunk connected to the packet network, a second trunk connected to a public network having a different protocol from that of the packet network, a monitoring module which monitors the call processing server, and when a failure occurs in the call processing server, deactivates the first trunk, and a call control module which transfers a transmission request which is made from the telephone terminal to the packet network to the second trunk when the transmission request is made and performs a detour transmission to the public network in a status where the first trunk is inactive.

Abstract: Embodiments of the present invention disclose a method for realizing direct dialing to an extension across Private Branch Exchanges (PBXs), in witch firstly a calling terminal of a PBX seizes a PBX circuit; secondly the calling terminal initiates a call to a called extension terminal in a PBX cluster by dialing a called extension terminal number directly; then a exchange system resolves the number of the PBX switchboard to which the calling terminal belongs according to a calling terminal number, and obtains a number of the PBX switchboard to which a called extension terminal belongs according to information of the called extension terminal number; and then the exchange system initiates a call to the PBX switchboard to which the called extension terminal belongs, and, when receiving an answer to the call from the PBX switchboard, sends the called extension terminal number, to connect the calling terminal with the called extension terminal.

Abstract: In one embodiment, method can include: receiving an address in a call agent, the address being associated with a call; triggering a trunk group selection algorithm in response to at least a portion of the received address, the trunk group selection algorithm providing a selection result from among a trunk group placeholder and a plurality of trunk groups; and forwarding the call to a trunk group determined by a caller-associated attribute when the selection result comprises the trunk group placeholder.

Abstract: A method is provided for reserving trunks on a trunk group for designated class of service calls. The trunks available for a denominated class of service is specified, and the trunks remaining are enumerated and designated as of no class and available for all calls. When the no class trunks are in use and a new call is a denominated class of service, it is allocated to a trunk and the trunks available is reduced accordingly. If the no class trunks are in use and a new call is not of a denominated class of service, the new call is allocated to a further trunk group. When a call is released and the number available is reduced below a specified number, the number of available trunks increases. If the number of trunks available is not reduced below a specified number, the released trunk is made available for all calls.

Abstract: The present invention relates to a method for establishing a call from a calling party to an extension of a PBX. By providing the calling party with a graphical display of information of extension of the PBX the user may easy and fast select a desired extension.

Abstract: Embodiments of the invention include a method for routing an Internet Protocol (IP)-based call through a first IP-based network to a second IP-based network. The method includes receiving an IP-based call request in the first network; identifying one or more geographic trunk groups that can be used to route the call request out of the first network, wherein each of the one or more geographic trunk groups represents a logical grouping of one or more IP trunk groups between the first IP-based network and the second IP-based network; selecting one of the one or more geographic trunk groups; and routing the received call request via the selected geographic trunk group to an IP address associated with the selected geographic trunk group. Other embodiments are also disclosed.

Abstract: It is one objective of the present invention to provide a private branch exchange that can identify calls to be routed to an extension phone group. A private branch exchange according to this invention comprises: a caller information detector for, when a call is received, obtaining caller information; a group incoming call table in which two or more extension numbers are correlated with an extension incoming call group number; and an incoming call group controller for, when a call received through the telephone line is for an extension incoming call group number, extracting from the group incoming call table extension numbers that are correlated with the extension incoming call group number and transmitting an incoming call signal to extension phones corresponding to the extension numbers, and also for storing, in a group incoming call log table, a caller number that is obtained by the caller information detector.

Abstract: A method of managing Voice over Internet Protocol (VoIP) calls with an Internet Protocol Private Branch Exchange (IP PBX) is provided, including: receiving at an IP PBX device an incoming call directed to a target telephone number, said IP PBX device storing a contact list parameter including one or more rule fields, each rule field including a telephone number identifier and an associated target extension identifier; searching the contact list parameter to identify the telephone number identifier corresponding to the target telephone number; and routing the incoming call to one or more target extensions corresponding to the target extension identifier associated with the identified telephone number identifier.

Abstract: A computer system 1 has a PBX 2, a terminal device 3, and a management server 4. The PBX 2 has a line controller, an extension controller 2b, an interface, a memory that stores identification information and an enciphered file, a decoder that decodes the enciphered file, a comparator that compares the identification information and the enciphered file decoded by the decoder, and a controller. The terminal device 3 reads the identification information from the PBX 2 and transmits that to the management server 4. The management server 4 has an authenticator that receives a request for authentication when the terminal device 3 logs in, an issuer that issues the enciphered file according to the identification information, and a database that stores the issue date in correlating with the identification information.

Abstract: A method and apparatus for identification of telephone numbers for IP telephones in offices to be assigned to different persons by (1) assigning one of the offices to one of the persons upon a request from the one of persons; (2) accessing a physical network address for an IP telephone located in the assigned one of the offices; (3) obtaining a telephone number for the one of the persons; (4) determining from the accessed physical network address an IP address of the IP telephone; (5) transmitting a message having the telephone number and IP address to a telecommunication switching system to which the IP telephone is interconnected; and (6) assigning the telephone number to the IP address by the telecommunication switching system in response to the message thereby assigning the telephone number to the IP telephone.

Abstract: Embodiments of the invention include a method for routing an Internet Protocol (IP)-based call through a first IP-based network to a second IP-based network. The method includes receiving an IP-based call request in the first network; identifying one or more geographic trunk groups that can be used to route the call request out of the first network, wherein each of the one or more geographic trunk groups represents a logical grouping of one or more IP trunk groups between the first IP-based network and the second IP-based network; selecting one of the one or more geographic trunk groups; and routing the received call request via the selected geographic trunk group to an IP address associated with the selected geographic trunk group. Other embodiments are also disclosed.

Abstract: In one embodiment, method can include: receiving an address in a call agent, the address being associated with a call; triggering a trunk group selection algorithm in response to at least a portion of the received address, the trunk group selection algorithm providing a selection result from among a trunk group placeholder and a plurality of trunk groups; and forwarding the call to a trunk group determined by a caller-associated attribute when the selection result comprises the trunk group placeholder.

Abstract: A method and system include routing telephone calls from multiple private networks via public lines and trunks in a public switched telephone network (PSTN) to a host switch, at which the connections would begin to run parallel. The host switch routes the telephone calls via a private trunk group to a private facility, such as an electronic tandem network (ETN) node or an asynchronous transfer mode (ATM) switch. If the private trunk group is full or unavailable, the host switch routes the telephone calls over alternate private or public trunk groups and selected carriers.

Abstract: It is one objective of the present invention to provide a private branch exchange that can identify calls to be routed to an extension phone group. A private branch exchange according to this invention comprises: a caller information detector for, when a call is received, obtaining caller information; a group incoming call table in which two or more extension numbers are correlated with an extension incoming call group number; and an incoming call group controller for, when a call received through the telephone line is for an extension incoming call group number, extracting from the group incoming call table extension numbers that are correlated with the extension incoming call group number and transmitting an incoming call signal to extension phones corresponding to the extension numbers, and also for storing, in a group incoming call log table, a caller number that is obtained by the caller information detector.

Abstract: A method and system include routing telephone calls from multiple private networks via public lines and trunks in a public switched telephone network (PSTN) to a host switch, at which the connections would begin to run parallel. The host switch routes the telephone calls via a private trunk group to a private facility, such as an electronic tandem network (ETN) node or an asynchronous transfer mode (ATM) switch. If the private trunk group is full or unavailable, the host switch routes the telephone calls over alternate private or public trunk groups and selected carriers.

Abstract: A system for handling special number calls placed from a phone coupled at a connection locus in a private network; includes: (a) a private switch controlling communications with the phone from outside the private network during a call session; (b) a control facility coupled with the private switch and with a special number call system for effecting communications between the private network and the special number call system; and (c) a contact parameter storage unit coupled with at least one of the private switch and the special number call system for identifying at least one contact parameter relating to the connection locus at least during the call session. The private switch, the control facility and the special number call system cooperate in using the contact parameter to effect call back from the special number call system to the phone at least during the call session.

Abstract: The present invention provides a method and apparatus for monitoring a trunked radio communications system by using some type of radio scanning receiver that is not designed for that purpose. In addition, the invention provides a method for automatically determining the polarity of the received control channel data. Further, the invention provides a method for automatically determining the type of trunked radio communications system. In addition the invention provides a method for automatically determining the channels in a trunked radio system and a method for automatically determining the bit rate of transmitted digital signals over a control channel of a trunked radio communications system.

Abstract: A telephony system for completing conference calls includes a premise-based network having a local controller coupled to local endpoints, a proxy, and a conference bridge. The telephony system includes a public telephone network coupled to the premise-based network. A request call is initiated to the proxy for setting up the conference call. The request call is routed to the conference bridge. A plurality of local endpoints for participation in the conference call is provided to the proxy via the request call. The local controller contacts the plurality of local endpoints and routes successful connections to the conference bridge. The request call and the successful connections are then bridged at the conference bridge.

Abstract: Each of a plurality of mobile stations is provided with a plurality of extension numbers including at least one unique extension number, and different lines are set for the plurality of extension numbers respectively. This enables a call using a line even when another call is made using another line.

Abstract: A PSTN (Public Switching Telephone Network) device includes a Dynamically Configurable Signaling State Machine (DCSSM). The DCSSM can be programmed to recognize multiple signaling templates. The DCSSM can also be programmed to modify existing recognized standardized signaling templates. Programming is accomplished via a configuration interface. Commands are sent to the DCRSSM via the PSTN device's configuration interface. When the trunk controller receives a signal or is required to transmit a signal, the DCSSM executes the directives configured with the programmed signaling templates within a signaling state machine.

Abstract: Planning alternative SS7 networks is a complex task requiring assistance from an intelligent planning tool. The tool includes at least one planning database containing information on network traffic, component locations, and component connectivity. A load module determines peak load for each STP in the core network. A forecast module determines equipment capacity exhaustion for each STP, network database, and core link during each study period and determines network costs based on peak loads and an alternative network design provided by a user. A graphical user interface guides the user through a sequence of design steps, each step having to be correctly completed before the next step in the sequence is started. The sequence of steps may include permitting changes to the core network, permitting changes to the number of POPs and DBs, rehoming elements left disconnected from STPs, assigning SSPs to POPs, assigning SSPs to DBs, and permitting voluntary rehomes.

Abstract: A method for interface an IPABX and a local exchange includes the steps of: processing a call originated from an IPABX by a local exchange having one discernible individual by binding a plurality of data transmission lines, that is, a data transmission line trunk group; and processing a call destined to the IPABX through the local exchange. Since the directory number can be managed by a group name, stepping up from the method for fixing the directory number to the line, the expense for the line can be reduced. In addition, the problem of separation between the origination line and the destination line as in the conventional method that the trunk line and the PRI line are together used is settled. Moreover, since there is no need to allocate an additional signaling point, an expense possibly incurred for the allocation of a signaling point and consumption of the signaling point resource can be prevented.

Abstract: A method of rerouting telephone calls directed to a private branch exchange (PBX) located at a first site to a second site wherein the PBX has at least one nonfunctional routing number is provided. The method includes providing a corporate long distance telephone system, providing a telephone hunt group, programming a plurality of routing numbers assigned to the first site PBX such that calls directed to the first site PBX are routed through the corporate long distance telephone system to the telephone hunt group, programming the hunt group to forward calls to a dedicated long distance telephone system, and programming the dedicated long distance telephone system to route calls to at least one of an alternate PBX and a dedicated wireless telephone system located at the second site.

Abstract: Features available in one communication installation of a communication system are made available system-wide by transmitting an item of feature control information for a subscriber line of a first communication installation to a second communication installation. The item of feature control information is converted into at least one function call, whose associated function is provided by a computer telephony integration (CTI) interface. The function call is transmitted via the CTI interface to the first communication installation. At least one feature control instruction contained in the function call is executed by an administration and maintenance device of the first communication installation. The first communication installation depicts a controlled instance with regard to a feature control, while the second communication installation depicts a controlling instance.

Abstract: A method of load testing an IP PBX. The IP PBX is connected to a LAN, to which a registration simulator is also connected. The registration simulator is used to load the IP PBX with registrations. Actual phone calls are then made on the LAN, to determine whether the loading has adversely affected performance of the IP PBX. In this manner, the maximum CPU capacity of the IP PBX can be determined.

Abstract: The present invention refers to a telephone exchange, a telephone system comprising such an exchange as well as a method for connecting a computer to a computer network via an exchange and a telecommunication network, where the exchange comprises a switch core, a switch control means responsible for setting up connections between users of the exchange and at least one network connection device that is connected between the switch core and the computer network. The network connection device comprises a signal processing means that converts the signal structure of data signals, received from computers via the telecommunication network and the switch core, to data packets having a signal structure suitable for data communication and supplies these data packets to the computer network. The exchange comprises means for monitoring every connection set up between such a computer and the computer network.

Abstract: A method and system include routing telephone calls from multiple private networks via public lines and trunks in a public switched telephone network (PSTN) to a host switch, at which the connections would begin to run parallel. The host switch routes the telephone calls via a private trunk group to a private facility, such as an electronic tandem network (ETN) node or an asynchronous transfer mode (ATM) switch. If the private trunk group is full or unavailable, the host switch routes the telephone calls over alternate private or public trunk groups and selected carriers.

Abstract: The invention is a novel method of processing incoming and outgoing call requests by a switching unit such as a KSU, PBX or PC server. Each established circuit and each call request is associated with a priority. For an outgoing call request, if an available external bandwidth channel of the appropriate type is found, then a circuit is established at once. However, if there is no available external bandwidth channel of the appropriate type, then the priority of the outgoing call request is checked against the priority of the established circuits. If a lower-priority circuit is found, then that circuit is torn down and a new circuit is established between the internal bandwidth channel carrying the outgoing call request and the external bandwidth channel formerly occupying the established circuit that was torn down. In the case of an incoming call request, a destination terminal device and associated internal bandwidth channels will be specified and availability thereof is verified.

Abstract: A telecommunication management system drawn to processing communication between a client application single user interface, a master database, and a PBX and adjunct system, comprising connecting to the client application single user interface through a first communication channel; registering a client application; adding a second communication channel; subscribing to one or more message events from a sender; reading and posting the subscribed one or more message events; and disconnecting from the client application single user interface.

Abstract: A telephony network includes a number of switches that are coupled by respective trunk sets. In one or more of the switches, both a main queue storing identifiers of trunks that are available and a shadow queue are maintained. The shadow queue is used to store identifiers of available trunks in an order that tracks the order of a corresponding queue in a switch on the other end of the trunk set. By using both the contents of the main queue and the shadow queue to perform selection, trunk glare can be reduced.

Abstract: A telecommunications management system that deploys a single-point-of-entry and synchronous database system. In addition to controlling commonly used PBX systems, the management system controls adjunct systems such as voice mail and 911 emergency systems by synchronizing the entry of data for a user from a telephone system into a master database for a single data record. The system also includes global synchronization in which a record-by-record comparison of the master database with the entries found in the telephone or adjunct system, or visa versa, is made. If the record is found, then the properties are updated with the information form either the master database or the telephone or adjunct system. The system includes the feature of synchronizing without update, which allows the user to see exactly what the manger will do to complete synchronization prior to synchronization taking place.

Abstract: In an exchange including: a call processing unit for processing a call occuring at any one of plural subscriber lines, a main line, or a private line; a switch unit for establishing the call route determined by the call processing unit; and a plurality of trunks for separately connecting to any one of these lines; wherein the exchange comprises: a single or plural decision units for determining whether an audio frequency signal or line signal which separately indicates a state of change of level of the call signal, is received or not, in the route formed by these lines; and a single or plural variable units separately provided between each of routes and a corresponding port of the switch, and performing the change of the level based on the state indicated by the audio frequency signal or line signal which gives a result of decision by the decision unit, for the level of the call signal transmitted toward the route in which the result of the decision is true.

Abstract: A method in which at least one memory, which is associated with at least one first subscriber connection, is used to store a cross-reference to a second subscriber connection whose state is signaled at the first subscriber connection. For allocation of the first subscriber connection to a first communications system and allocation of the second subscriber connection to a second communications system, the at least one first subscriber connection is allocated group information, and the group information is stored, for message compression, in a memory which is associated with the second subscriber connection. Furthermore, in the event of a state change of the second subscriber connection, a message relating to the state change is sent with the group information to the first communications system, for transmission of a message with information about the state change to the first subscriber connection.

Abstract: A method for managing messages in a private branch exchange system uses a personal computer as an operator console. The method includes storing a message to be transmitted to a subscriber who is absent through the personal computer; if there is a call from the subscriber, transmitting a call message from the subscriber indicating whether the call is for confirming the message or is a general call to the personal computer; if the call message is for confirming the message, automatically displaying the message to be transmitted to the subscriber on a monitor of the personal computer; and informing the subscriber of the displayed message.

Abstract: Key telephone system with a private branch exchange that includes a switching unit, stationary key terminals, and at least one of mobile cordless and GSM terminals. The switching unit is adapted to switch calls to the stationary key terminals and to the at least one of the mobile cordless and GSM terminals. The system also includes a first trunk group and a key server system, in which the stationary key terminals are coupled to the switching unit through the first trunk group and the key server system, at least one additional server comprising a memory unit, and a second trunk group having lines associated with each of the at least one of the mobile cordless and GSM terminals.

Abstract: A telecommunications system incorporates a switch based private network having a transparent network signalling system and having a plurality of nodes interfacing each via a switch with an intelligent public network. The public network incorporates a service control point having associated therewith a database containing destination addresses corresponding to call numbers received from the private network. The database provides routing data for call independent signalling information in response to requests from a node on behalf of a private service provided to a user of that node and from a public network switch on behalf of a private service provided to a directly connected user of that switch.

Abstract: A method for transmitting calls between interconnected PBX systems within a private telephone network is disclosed. An initial call connection request is generated at an originating PBX system to a destination PBX system. The call connection request includes an indication of a specific destination number which may answer a call to the exclusion of any other destination number. If the specific destination number may not answer the call, the originating PBX system is notified of the call connection failure and the originating PBX accesses a pre-generated listing of alternate call destinations. Call connection then proceeds to one of the alternate destinations.

Abstract: A method, in an electronic switching system comprising a main processor and line processors which can adapt K number of signaling types, N and K being positive integers, respectively, wherein the system is connected to another electronic switching system at trunk ports through trunk lines and the main processor includes a database for the line processors, route data, prefix data and state of the trunks including the trunk lines and the trunk ports, comprises the steps of: identifying a signaling type of a line processor; informing the identified signaling type to an operator; checking whether the trunk port connected to the line processor adapts the identified signaling type or not if the operator decides to change the identified signaling type; deleting data of the trunk in the main processor's database and assigning a new signaling type to the line processor if said trunk port adapts the identified signaling type, wherein the new signaling type is a same signaling type as used in said another electronic swi

Abstract: A LEC bypass technique which provides analog voice grade communications from a caller to an independent Central Office (CO) for local services and/or to a long distance inter-exchange carrier ("IXC") for long distance services by utilizing existing tariffed network data services and existing tariffed commercial DID/DOD services. The telephone switching equipment of an Independent Central Office is located in a new residential housing development (single detached, attached, or multi-family) or a new commercial development and used to provide local and long distance calling services, as well as Internet access and other telecommunications services, to the residents of the residential housing development or the tenants of the commercial development.

Abstract: A private communication system and an allocated, private communication terminal equipment that is not directly connectable, i.e. that is "external", has a respective terminal equipment emulation unit allocated to it. This terminal equipment emulation unit pair are connectable to one another at least via a public dialed communication network, where the connection of at least one message path and of an additional signaling path is controlled via the public dialed communication network and the switching of the paths suited to the terminal equipment emulation unit pair is checked. With the assistance of the terminal equipment emulation unit pair, isolated or external communication terminal equipment can be connected without diminishing the scope of performance features of private communication networks. Misconnections and false signalings are avoided by checking the connection suited to the terminal equipment emulation unit pair with the assistance of a specific check procedure.

Abstract: A telecommunication system including a telecommunication exchange and a controller for establishing and controlling connections between parties directly coupled to the telecommunication exchange. The controller establishes party processes associated with the parties and the party processes are established after at least two parties are directly coupled to said telecommunication exchange. The system also establishes signaling messages which are exchangeable between the party processes and indicate a changing status of one of the parties. The controller monitors the signaling messages and generates status information in response thereto while a processor receives the status information. The status information is made accessible to selected parties.

Abstract: A telephone exchange system useful for a dealing speech system or the like is disclosed, which can accommodate large numbers of lines (or trunks) and permit improvement of the reliability and call connection processing capacity. The system comprises exchange sub-systems A (EX-A) and B (EX-B) capable of independently executing an exchange operation and each accommodating a terminal. The terminal has a speech channel switch for connecting a speech channel including a handset to either exchange sub-system A (EX-A) or B (EX-B). When the process of connecting a call is brought about in the terminal, it selects one of the exchange sub-systems and controls the speech channel switch for connecting the call to the selected exchange sub-system.