Abstract: A method, system and gateway device enables interworking between an IP-based network and a circuit-switched network. A first address information of a first connection end located in the circuit-switched network is routed in a trigger message from the IP-based network to a gateway control function. The first and second call legs are established in parallel towards the first connection end based on the first address information, and towards a second connection end located in the IP-based network based on a second address information obtained from the trigger message. A single connection between the two connection ends is then established by connecting the first and second call legs. Thereby, IP-based signaling functionality can be used to add capability for subscribers located in the CS domain to be invited into conferences or calls with subscribers located in an IP-based domain, e.g. the IMS domain.

Abstract: A method and arrangement for implementing the acquisition of data relating to network-specific supplementary services and a method for updating subscriber data relating to network-specific supplementary services in a telecommunications system. The subscriber data relating to the network-specific supplementary services is permanently stored in a subscriber identity module (12) of a user terminal. The user terminal (11) is arranged, at least when registering in a visited network (30), to automatically transmit the subscriber data relating to the supplementary services of the visited network (30) for temporary storage to the subscriber database (34) of the visited network (30).