bject to the Terms of Use as given at the website. ANSI-41 Signaling Capacity ANSI-41 Signaling Capacity The serving MSC sends a location cancellation message through its VLR to the HLR when the user terminal sends a power-down message or when the user terminal fails to register when it is required to do SO. This message is acknowledged by the HLR. When the user terminal registers in a new MSC region while still qualified for ser- vice in another MSC region, the HLR sends a registration cancellation message through its VLR to the HLR, which is acknowledged. In code division multiple access (CDMA) systems, there also can be an exchange of information between the old and new MSC regions directly, two more messages between their VLRs. There are also messages and acknowledgments when the HLR revokes the service qualification it has sent or when the subscriber activates a feature. These are far rarer events, we hope, than the normal, successful registration of a user terminal. Registration uses two messages from serving MSC to serving VLR to HLR and back to turn on the user terminal, four messages to move to a new MSC region, two more messages to move within the MSC region if subregions of service have been defined, and two more messages for a timeout. Finally, there are two more messages when the user terminal is turned off or otherwise loses connection with the serving MSC. When two MSC regions have border cells as described in Sec. 15.2.3, user terminal registration can be detected by a base station served by an MSC other than the serv- ing MSC. When the border MSC receives a registration message, it sends a message re- questing service qualification to the HLR, so the HLR receives two messages. The HLR resolves the two MSCs based on their reported radio signal conditions and sends a mes- sage to the serving MSC, either an acknowledgment of its request or a cancellation. Once the serving MSC replies, the HLR sends the border MSC a message. Thus a border-cell detection generates two messages between the border MSC a