combinational networks may provide simultaneous connectivity over networks of different type between user equipment of an a - party and b - party . a communication session , comprising a circuit switched call and one or more packet switched sessions , may be deployed simultaneously over different network types , in relation to the same user equipment . the circuit switched call and the packet switched session may be correlated . as to retrieve the packet switched address of a circuit switched call partner , a retrieval for a packet switched network address is initialized by means of a circuit switched protocol over a circuit switched network . the address retrieval request is directed to the call partner or a network node that accomplishes the network address request .