Method of and apparatus for use in forwarding calls intended for roaming subscriber units
View Patent ↗A method for use in forwarding a call intended for a GSM-roaming subscriber unit ( 106 ) is performed by a mobility gateway ( 102 ) connected between an ANSI-41 network and a GSM network. The method includes associating the roaming subscriber unit ( 106 ) with one of a plurality of temporary transfer-to telephone numbers homed on a mobile switching center ( 118 ). The temporary transfer-to telephone number is used for an intermediate and temporary transfer of a call intended for the roaming subscriber unit ( 106 ) in response to some predetermined condition, such as a busy indication or expiration of time. This number is used to facilitate both the forwarding of the call to a voice mail system ( 116 ) and the tearing down of international long-distance connections.
1. A method for use in a mobility gateway for forwarding a call directed to a roaming subscriber unit, the method comprising:
storing in memory, at the mobility gateway coupled between a GSM network and an ANSI-41 based network, a plurality of temporary transfer-to telephone numbers;
selecting, for association with the roaming subscriber unit, one of the temporary transfer-to telephone numbers;
sending a message having the temporary transfer-to telephone number to a mobile switching center serving the roaming subscriber unit;
after selecting and sending, receiving, and storing information related to a call request for the roaming subscriber unit: and
after receiving and storing, receiving a location request message from a mobile switching center which homes the temporary transfer-to telephone number.
2. The method according to claim 1 , wherein the temporary
transfer-to telephone number is homed on a mobile switching center that is different from a mobile switching center serving the roaming subscriber unit.
3. The method according to claim 1 , further comprising:
associating the location request message with the call request for the roaming subscriber unit.
4. The method according to claim 3 , further comprising:
after associating, sending a redirection request message to a gateway mobile switching center which received the call request.
5. The method according to claim 1 , further comprising:
associating the location request message with the call request for the roaming subscriber unit based at least in part on the temporary transfer-to telephone number.
6. A mobility gateway for use in connection between an ANSI-41-based network and a GSM-based network, the mobility gateway comprising:
a processor;
memory for storing a plurality of temporary transfer-to telephone numbers homed on one or more mobile switching centers (MSCs) that is different from a mobile switching center serving a roaming subscriber unit:
said processor being operative for:
selecting one of the plurality of temporary transfer-to telephone numbers for association with the roaming subscriber unit;
sending a message having the temporary transfer-to telephone number to a GSM MSC serving the roaming subscriber unit;
after selecting and sending, receiving and storing information related to a call request for the roaming subscriber unit; and
after receiving and storing, receiving a location request message from an MSC which homes the temporary transfer-to telephone number.
7. The mobility gateway according to claim 6 , wherein the selected temporary transfer-to telephone number associated with the roaming subscriber unit is homed on an ANSI-41 MSC different from a GSM MSC serving the roaming subscriber unit.
8. The mobility gateway according to claim 6 , wherein said processor is further operative for:
associating the location request message with the call request for the roaming subscriber unit.
9. The mobility gateway according to claim 8 , wherein said processor is further operative for:
after associating, sending a redirection request message to an ANSI gateway MSC Which received the call request.
10. The mobility gateway according to claim 6 , wherein said processor is further operative for:
associating the location request message with the call request for the roaming subscriber unit based at least in part on the temporary tansfer-to telephone number.
11. A method for use in forwarding a call between an ANSI-41 based network and a GSM-based network intended for a subscriber unit, comprising:
receiving and storing information related to a call request for a roaming subscriber unit;
after receiving and storing, receiving a location request message from a mobile switching center which homes a temporary transfer-to telephone number associated with the roaming subscriber unit;
after receiving a location request message from a mobile switching center, correlating the message with a previous request message received by a mobility gateway;
associating the location request message with the call request for the roaming subscriber unit; and
after associating, sending a redirection request message to a gateway mobile switching center which received the call request for the roaming subscriber unit.
12. The method according to claim 11 , further comprising, prior to receiving and storing the information related to the call request:
selecting the temporary transfer-to telephone number for association with a roaming subscriber unit; and
sending a message having the temporary transfer-to telephone number to a mobile switching center serving the roaming subscriber unit.
13. The method according to claim 11 , further comprising:
wherein the receiving and storing of information related to the call request includes receiving and storing information comprising subscriber identification information and call identification information; and
wherein sending the redirection request message includes sending the call identification information.
14. The method according to claim 11 , further comprising:
wherein receiving the location request message comprises receiving the temporary transfer-to telephone number; and
wherein associating the location request message with the call request comprises associating based on the temporary transfer-to telephone number.
15. A method for use in a mobility gateway coupled between an ANSI-41 based network and a GSM-based network, comprising:
selecting a temporary transfer-to telephone number for association with a roaming subscriber unit;
sending a message having the temporary transfer-to telephone number to a mobile switching center serving the roaming subscriber unit;
after selecting and sending, receiving and storing information related to a call request for the roaming subscriber unit;
after receiving and storing, receiving a location request message from a mobile switching center which homes the temporary transfer-to telephone number;
after receiving a location request message from a mobile switching center, correlating the message with a previous request message received by a mobility gateway;
associating the location request message with the call request for the roaming subscriber unit; and
after associating, sending a redirection request message to a gateway mobile switching center which received the call request for the roaming subscriber unit.
16. The method according to claim 15 , further comprising:
wherein the receiving and storing of information related to the call request includes receiving and storing information comprising subscriber identification information and call identification information; and
wherein sending the redirection request message includes sending the call identification information.
17. The method according to claim 15 , wherein the mobile switching center serving the roaming subscriber unit comprises a GSM mobile switching center and the gateway mobile switching center comprises an ANSI gateway mobile switching center.