A method and apparatus for sharing a single data channel for multiple signaling flows destined to multiple core networks are disclosed. For example, the method receives a plurality of service requests from a plurality of corresponding service clients on a single mobile endpoint device, where each of the plurality of corresponding service clients is to be registered with a different corresponding Internet Protocol Multimedia Subsystem (IMS) network. The method establishes the single data channel to support a plurality of signaling flows associated with the plurality of service requests simultaneously, and routes each signaling message associated with the plurality of service requests to the corresponding IMS network.