Patent ID: 10313998

Abstract:
When a cellular telephone is powered down, it sends a power-down message to a network it was previously registered with. If the network does not send, or if the cellular telephone does not receive, an acknowledgement of the power-down message from the network, a status bit referred to as a flag is set (or reset) in a non-volatile memory device in the cellular telephone. The power-down sequence is concluded by the cellular telephone and, the cellular telephone is shut off or put into a reduced power consumption state. When the telephone is turned back on, i.e., returned to its previous state, the flag is evaluated or “tested” to see if it was set (or reset) during the course of powering down. The status or value of the flag when the phone is powered up is then used by the cellular telephone to determine whether it should make a network access request to a network the telephone was registered to, during the power-up operation in order to cause that cellular network to update its database regarding the whereabouts of the powered-up cellular telephone.