Telecommunications system

Abstract

The use of multiple AAL2 virtual circuits to support narrow band calls with multiple types of narrow band signalling systems leads to inefficient use of bandwidths over an ATM network. The present invention provides a method of transporting narrow band calls of multiple narrow band signalling type between narrow band networks across a single virtual circuit in an ATM network, where for each call connection within a circuit the call connection signalling information includes the narrow band signalling type.

1 . A method of transporting narrowband calls of multiple narrowband signalling type between first and second narrow band networks across a virtual circuit in an ATM network, wherein for each call connection within said circuit the call connection signalling information includes the narrowband signalling type.  
     
     
         2 . A method as claimed in  claim 1  wherein the call connection signalling information is a data packet comprising a narrowband signalling type field.  
     
     
         3 . A method of transporting narrowband calls of multiple narrowband signalling type between first and second narrow band networks across an ATM network; the method comprising: 
 forming a virtual circuit;    forming call connections within said circuit with a call connection signalling information data packet comprising a narrowband signalling type field containing the narrowband signalling type of said call.    
     
     
         5 . An apparatus for transporting narrowband calls of different signalling type between first and second narrow band networks across an ATM network, the apparatus comprising: 
 means for forming a virtual circuit;    means for forming call connections within said circuit by receiving a call connection data packet comprising a narrowband signalling system type field containing the narrowband signalling system type of said call.    
     
     
         6 . An apparatus as claimed in claim  4 , wherein said means is an interworking function.  
     
     
         7 . An apparatus as claimed in  claim 5 , wherein said means is an interworking function.  
     
     
         8 . An apparatus as claimed in any one of claim  4 , wherein said virtual circuit is an AAL2 virtual circuit.