1. For use in a telecommunication network, a switch comprising: a plurality of call control agent functions, at least two of the call control agent functions associated with different signaling protocols, the signaling protocols defining a plurality of signaling control primitives; and a call control function operable to control routing of telephone calls through the switch, wherein the call control function is accessed using an application programming interface (API), the API comprising a plurality of classes defining objects representing the signaling control primitives.