Abstract: According to an embodiment of the present invention, a system is provided that includes a cellular network, a Public Switched Telephone Network (PSTN) and a mobile IP-telephony network (MIPTN). Both the cellular network and the MIPTN include a Home Function and one or more visited Functions. MIPTN subscribers can roam within the MIPTN. Also, a Gateway Function interfaces the PSTN and the MIPTN to allow roaming between the cellular network and the MIPTN. The Gateway Function performs a dynamic mapping function between PSTN/cellular addresses (e.g., in E.164 format) and MIPTN addresses (e.g., IP addresses) to allow registration and call delivery for subscribers roaming between the cellular network and the MIPTN. A similar type of Gateway Function also allows Short Message Service (SMS) messages to be delivered over the MIPTN as well.

Abstract: The invention relates to a method for application-specific quality of service optimization, in which method the processing of data streams coming from said application is optimized in nodes (2a, 2b, 2c, 2d) between a sender (1a) and a receiver (1b) in a communication network. In this communication network, at least one quality of service signalling protocol is used. The application uses this quality of service signalling protocol to mark application-specific data streams, wherein the nodes (2a, 2b, 2c, 2d) of the communication network identify, on the basis of the quality of service signalling, packets (3) belonging to the data stream of said application, and their type, wherein these packets (3) are subjected to optimization methods characteristic to this type.