Multiplexing system for ISDN circuits

Abstract

A multiplexing system for ISDN circuits. Multiplexers in the system include data terminals, voice interfaces having voice trunks, high speed digital circuits and ISDN circuits, together with a control channel interface which connects trunking circuits by controlling calls on the control channel. When an outgoing voice call originates, data information from data terminals voice is multiplexed with compressed information from a voice interface and transmitted to trunking circuits. When calls originate, the control channel controls calls and connects them with trunking circuits. When using ISDN circuits, after setting up a communication channel for the circuits, a CPU controls calls to multiplex ISDN circuits on the control channel. By this structure decreasing the multiplexing ratio due to voice multiplexing call control on ISDN circuits can be eliminated when linking multiplexers with communication channels having high speed digital circuits and ISDN circuits.

What is claimed is:  
     
       1. A multiplexing system, comprising: 
       a plurality of call stations, each call station including a data terminal, a voice terminal, a voice compressor for compressing voice information from said voice terminal, and a multiplexing device for multiplexing data information from said data terminal and compressed voice information from said voice compressor;  
       a high speed digital circuit having a control channel for controlling circuit connections between call stations and a communication channel for communicating voice and data information between call stations;  
       an ISDN circuit having a control channel for controlling circuit connections between call stations and a communication channel for communicating voice and data information between call stations;  
       a controller responsive to origination of voice and data information at a first call station to be communicated to a second call station for transmitting call control information on the control channel of said high speed digital circuit to control communication of the voice and data information on said high speed digital circuit from the first call station to the second call station, and responsive to the communication paths on said high speed digital circuit being unavailable, for setting a communication path on said ISDN circuit between the first call station and the second call station and transmitting the call control information on the control channel of said high speed digital circuit for communication of the voice and data information on the set communication path on said ISDN circuit so as to communicate calls of multiplexed data information and compressed voice information on one communication path using only necessary bandwidth.  
     
     
       2. A multiplexing system as set forth in  claim 1 , wherein said multiplexing device further includes means for including identification information of a generating call station and a receiving call station of the communication in the call control information transmitted on the control channel of said high speed digital circuit. 
     
     
       3. A multiplexing system as set forth in  claim 2 , wherein said multiplexing device further includes means responsive to receipt of the call control information on the control channel of said high speed digital circuit for the communication using the communication channel of said ISDN circuit, for determining the identification of the receiving call station to which the information is addressed, and if the information is addressed to another call station, transferring the information to said another call station. 
     
     
       4. A multiplexing system as set forth in  claim 1 , wherein said multiplexing device further includes means responsive to a new call being originated while a communication path is established on said ISDN circuit, for determining whether there is any vacancy in the communication channel on said high speed digital circuit, and if so, for giving priority to use of said high speed digital circuit. 
     
     
       5. A multiplexing system as set forth in  claim 1 , wherein said multiplexing device further includes means responsive to detection of termination of a call on the communication channel of said ISDN circuit for determining whether other calls exist on the communication channel of said ISDN circuit, and if not, for terminating the communication path on said ISDN circuit. 
     
     
       6. A multiplexing system, comprising: 
       
         a plurality of call stations connected via a high speed digital circuit, each of said plurality of call stations being connected via an ISDN circuit to an ISDN network;  
       
       
         each of said plurality of call stations including a data terminal, a voice terminal, a voice compressor for compressing voice information from said voice terminal, and a multiplexing device for multiplexing data information from said data terminal and compressed voice information from said voice compressor;  
       
         said high - speed digital circuit including a first control channel for sending and receiving call connect information between a first call station and a second call station for connecting the data terminal or voice terminal included in the first call station with the data terminal or voice terminal included in the second call station, and a first communication channel for sending and receiving data information or voice information between said data terminal or voice terminal included in the first call station and said data terminal or voice terminal included in the second call station;    
       
         said ISDN circuit including a second communication channel and a second control channel, wherein call connect information for setting said second communication channel between said first call station and said second call station via said ISDN network is sent and received through said second control channel;  
       
       
         each of said call stations further having a connect control means, characterized in that:  
       
       
         when generating a call from said data terminal or voice terminal, said first control channel in said high speed digital circuit performs call control for setting within said first communication channel in said high speed digital circuit a communication path for sending and receiving data information or voice information between said data terminal or voice terminal included in the first call station and said data terminal or voice terminal included in the second call station; and  
       
       
         upon generating a call from said data terminal or voice terminal, when said first communication channel in said high speed digital connect cannot be used, said second control channel in said ISDN circuit performs call control for setting said second communication channel between said first call station and said second call station via said ISDN network, and thereafter said first control channel in said high speed digital circuit performs call control between said first call station and said second call station and sets within said second communication channel in said ISDN circuit a communication path for sending and receiving data information or voice information between said data terminal or voice terminal included in said first call station and said data terminal or voice terminal included in said second call station. 
       
     
     
       7. A multiplexing system according to  claim 6 , wherein each of said call stations further comprises means for including in the call connect information transmitted on the second control channel of the ISDN circuit identification information identifying the first call station as the generating call station of the communication and identifying the second call station as the receiving call station of the communication. 
     
     
       8. A multiplexing system according to  claim 7 , wherein each of said call stations further comprises transfer means responsive to receipt of call connect information of the ISDN circuit via said second control channel, for referring to identification information included in the call connect information, determining whether the call connect information is addressed to itself or not, and when the call connect information is addressed to another call station, transferring the call connect information to said another call station. 
     
     
       9. A multiplexing system according to  claim 6 , further comprising means responsive to a new call being originated by said data terminal or voice terminal included in the first call station while said second communication channel is established on said ISDN circuit, for determining whether there is any vacancy in said first communication channel, and if so, for giving priority to use of said first communication channel. 
     
     
       10. A multiplexing system according to  claim 6 , further comprising call control means responsive to detection of termination of a call on said second communication channel for determining whether other calls exist that utilize said second communication channel, and if not, performing call control for disconnecting said second communication channel that has been set via said ISDN network.