Method and apparatus for supporting machine-to-machine (M2M) communications in a hierarchical network architecture including an M2M gateway are disclosed. An M2M entity, (such as M2M device, M2M gateway, or M2M network entity), may perform a service capability discovery procedure to discover an M2M service capability entity that may provide an M2M service capability, and register with the discovered M2M service capability entity. The address or identity of the service capability entity may be pre-configured or obtained from the dispatcher server. The M2M entity may indicate a support M2M service identifier and receive an identity or address of the M2M service capability entity mapping the service identifier. The gateway may advertise M2M service identifiers supported by the gateway so that the M2M device may access the gateway if there is a match. The address of M2M service capability entities may be obtained from the core network.