Abstract: In a telecommunication system having a plurality of cooperating exchanges and using a separate signaling network, an existing exchange is replaced by a new exchange by a piecemeal transferring of interexchange trunks from the existing exchange to the new exchange and testing the trunks on the new exchange. All signaling messages pertaining to trunks originally resident on the existing exchange are addressed to the existing exchange, are intercepted and are selectively forwarded to the new exchange on the basis of recorded data defining trunks moved to the new exchange. One embodiment uses a point code converter connected between a signal transfer access point for the signaling network and both the old and the new exchange. The converter receives all messages addressed to the existing exchange and transfers the messages to either the old or the new exchange, depending on the present location of the trunk.