Abstract: A method, system, and apparatus enables a subscriber to be warned via the mobile terminal (MT) when the MT has moved into an invalid area during a call. The network monitors the location/position of the MT during a call. When the MT enters a region (e.g., a cell) that is invalid because it is located within an invalid area, the network sends a message to the MT. The message may be, for example, a novel cause code in a Direct Transfer Application Part (DTAP) message that triggers a warning action by the MT when the network does not have access to the transmission reaching the MT. The message may alternatively be an announcement or tone sent directly to the MT when the network does have direct access to the transmission reaching the MT. The network also begins a timer. If the MT is returned to a valid area before the is timer expires, the call may be continued (and a message so indicating may optionally be sent to the MT from the network).