Combined registration and call continuation method and apparatus for a mobile communication system

A method for location registration and call continuation for a communication unit (CU) in a communication system having a Mobile-Switch Interface (MSI) coupled to a Mobile services Switching Center (MSC), wherein the MSI provides an interface between the CU and the MSC, and the MSC interfaces the communication system with another communication system, the method performed by the MSI comprising the steps of:

• a) receiving, by the MSI, a first message from the CU which notifies the MSI that the CU is performing a location updating process;
• b) sending, by the MSI, a second message to the MSC in response to the first message, wherein the second message indicates that the CU is performing the location updating process;
• c) receiving, by the MSI, a third message from the MSC in response to the second message, the third message indicating that the location updating process has been completed;
• d) sending, by the MSI, a fourth message to the CU in response to the third message, wherein the fourth message indicates that the location updating process has been completed;
• e) determining, by the MSI, whether the CU has requested to use an additional system service;
• f) when the determining step indicates that the CU has not requested to use the additional system service, sending a fifth message to the CU which forces the CU to release a channel between the CU and the MSC;
• and
• g) when the determining step indicates that the CU has requested to use the additional system service, not sending the fifth message to the CU which would force the CU to release the channel even when the MSC has informed the MSI that the CU cannot, perform the additional system service.

A method for location registration and call continuation for a communication unit (CU) in a communication system having a Mobile-Switch Interface (MSI) coupled to a Mobile services Switching Center (MSC), wherein the MSI provides art interface between the CU and the MSC, and the MSC interfaces the communication system with another communication system, the method performed by the CU comprising the steps of:

• a) sending a first message which informs the MSI that the CU is performing a location updating process, and which also includes a first indicator which indicates that the CU has requested to use an additional system service after the location updating process;
• b) receiving a second message from the MSI in response to the first message, wherein the second message includes a second indicator which indicates that the CU can use the additional system service, and wherein the MSI has ensured that the second indicator indicates that the CU can perform the additional system service even when the MSC has informed the MSI that the CU cannot perform the additional system service;
• and
• c) using the additional system service after the location updating process.

A Mobile Switch interface (MSI) apparatus for use in a communication system having a Communication Unit (CU), the MSI apparatus, and a Mobile Switching Center (MSC), wherein the MSI apparatus provides an interface between the CU and the MSC, and the MSC enables the communication system to communicate with another communication system, the MSI apparatus comprising:

• at least one receiver for receiving a first message from the CU, wherein the first message indicates that the CU is performing a location updating process, the at least one receiver also for receiving a second message from the MSC, the second message indicating whether the MSC allow the CU to utilize an additional system service after the location updating process is completed;
• a controller coupled to the at least one receiver for determining whether the CU has requested to utilize the additional system service after the location updating process, wherein when the CU has not requested to utilize the additional system service, the controller for forcing the CU to release a channel between the CU and the MSI, and when the CU has requested to utilize the additional system service;
• not forcing the CU to release the channel;
• and
• at least one transmitter coupled to the controller for sending a third message to the MSC in response to the first message, the third message for informing the MSC that the CU is performing the location updating process, the at least one transmitter also for sending a fourth message to the CU in response to the second message, the fourth message for informing the CU whether the CU may utilize the additional system service, wherein when the second message indicated that the CU has requested to utilize the additional system service, the fourth message will inform the CU that the CU can utilize the additional system service even if the second message indicates that the MSC will not to allow the CU to utilize the additional system service.