Abstract

Method and apparatus are provided for transmitting calls generated by a first communication network over a second communication network to a third communication network wherein the first communication network operates in accordance with a first communication protocol which enables call services, the third communication network operates in accordance with a communication protocol which enables at least one of the call services enabled by the first communication protocol and the second communication network operates according to a second communication protocol different from the first. The apparatus includes elements to determine whether a call to be routed from the first communication network to the third communication network by means of the second communication network requires a call service to produce a data message compatible with the second communication protocol indicative of the required service and to transmit the call and data message over the second communication network to the third communication network, where the data message is read and an appropriate call service established to the third communication network. By producing a data message compatible with the second protocol to carry the call service information it is possible to establish a call service over a communications network even though that network does not explicitly support the call service.