In a mobile communication system including a circuit-switched (CS) mobile communications network, a packet-switched (PS) mobile communications network and an interworking function adapted to enable a signaling exchange between the CS and PS mobile communications network, a method of providing combinational CS+PS services to mobile users includes receiving, at a serving network entity in the PS mobile communications network, a user request issued from a first user on the PS mobile communications network, the user request relating to combinational services and having the serving network entity managing the received request, wherein the managing of the received request includes controlling an establishment of a session in the CS mobile communication network through the interworking function.