An Internet Protocol Multimedia Subsystem, IMS, wherein the IMS comprises a communication path allocating entity for allocating communication paths (21, 23, 25) in communication sessions between said IMS and a plurality of terminals including a first terminal, each of said terminals being connectable to said IMS via at least one of said communication paths (21, 23, 25), said communication path allocating entity comprising: a receiver for receiving a session request for requesting an establishment of a new communication session or a change in an existing communication session between said IMS and said first terminal, a processor for processing said session request and for independently allocating N downlink communication paths from said IMS to said first terminal and M uplink communication paths from said first terminal to said IMS for the new communication session or the changed communication session, where N ≥ 0, M ≥ 0 and M+N ≥ 1, wherein said communication paths (21, 23, 25) are provided over at least two different sub-networks (31, 32, 33) arranged for accessing said first terminal, and said processor is arranged to independently allocate communication paths (21, 23, 25) in said sub-networks (31, 32, 33) for said new communication session or said changed communication session, wherein said first terminal is a wireless terminal and wherein one of said allocated communication paths is provided over a circuit switched wireless access sub-network among said sub-networks (31, 32, 33) and another one of said allocated communication paths is provided over a packet switched wireless access sub-network among said sub-networks (31, 32, 33), wherein said processor is arranged for: - keeping a record of allocated communication paths (21, 23, 25) and their associated sessions in a session data base, and - using information from said session data base for the allocating. a receiver for receiving a session request for requesting an establishment of a new communication session or a change in an existing communication session between said IMS and said first terminal, a processor for processing said session request and for independently allocating N downlink communication paths from said IMS to said first terminal and M uplink communication paths from said first terminal to said IMS for the new communication session or the changed communication session, where N ≥ 0, M ≥ 0 and M+N ≥ 1, wherein said communication paths (21, 23, 25) are provided over at least two different sub-networks (31, 32, 33) arranged for accessing said first terminal, and said processor is arranged to independently allocate communication paths (21, 23, 25) in said sub-networks (31, 32, 33) for said new communication session or said changed communication session, wherein said first terminal is a wireless terminal and wherein one of said allocated communication paths is provided over a circuit switched wireless access sub-network among said sub-networks (31, 32, 33) and another one of said allocated communication paths is provided over a packet switched wireless access sub-network among said sub-networks (31, 32, 33), wherein said processor is arranged for: - keeping a record of allocated communication paths (21, 23, 25) and their associated sessions in a session data base, and - using information from said session data base for the allocating. - keeping a record of allocated communication paths (21, 23, 25) and their associated sessions in a session data base, and - using information from said session data base for the allocating.