A method and apparatus for transferring a session from a packet switched access network to a circuit switched access network. A Mobility Management Entity receives a service type indicator from a gateway node. The service type indicator indicates a type of service for the session, and is associated with bearers used for the session. The Mobility Management Entity subsequently receives, from an eNodeB, an indication that the session is to be transferred from the packet switched network to the circuit switched access network. The Mobility Management Entity determines the bearers associated with the session using the service type indicator, and initiates transfer of the session using those bearers. This ensures that the correct bearers are transferred regardless of whether or not identifiers such as QCI values have been ascribed to other types of service.