A telecommunications system having a first PS network, second PS network and a third circuit-switched core network includes a system for terminating a legacy domain circuit-switched communication upon receipt of a trigger signal requesting termination of communication. The system includes first and second functional entities in each network. The first and second functional entities of the first network can communicate signals over an interface using a PS protocol. The first and second functional entities of the second network can communicate signals over an interface using a PS protocol. The first functional entity of the first network can communicate packet data to and from the first functional entity of the second network. The second functional entity of the first network communicates a PS protocol signal to the second entity of the second network, which then communicates a circuit-switched protocol signal to and from the third circuit-switched protocol core network to terminate the circuit-switched communication.