A method of handling delayed signaling of a target mobile device for a first network control node is disclosed. The method comprises the first network control node receiving a request from a network gateway node; the registered network control node setting a flag and informing a data base to set the flag for the target mobile device when the first network control node fails to deliver the request to the target mobile device; and the first network control node sending the flag to a second network control node when the target mobile device is reachable in the second network control node.