Circuit Switched Fallback Proxy

A proxy operative to handle messages of a mobile user equipment (UE) in a mobile communications network, the mobile communications network comprising a first switching control node supporting Circuit Switched Fallback (CSFB) functionality, and a second switching control node not supporting the CSFB functionality, the proxy comprising:

• an interface configured to receive a message containing a Circuit Switched Fallback Mobile Originated (CSMO) call indicator or a Circuit Switched Fallback Mobile Terminated (CSMT) call indicator from the UE;
• and
• a control unit configured to:
• determine whether the CSMO call indicator or the CSMT call indicator is set in the received message;
• initiate a routing of the received message to the first switching control node if either the CSMO call indicator or the CSMT call indicator is set;
• and
• initiate a routing of the received message to the second switching control node if neither the CSMO call indicator nor the CSMT call indicator is set.

A method implemented by a proxy for handling messages of a mobile user equipment (UE) in a mobile communications network, the mobile communications network comprising a first switching control node supporting Circuit Switched Fallback (CSFB) functionality and a second switching control node not supporting the CSFB functionality, the method comprising:

• receiving a message containing a Circuit Switched Fallback Mobile Originated (CSMO) call indicator or a Circuit Switched Fallback Mobile Terminated (CSMT) call indicator from the UE;
• determining whether the CSMO call indicator or the CSMT call indicator is set in the received message;
• initiating routing of the received message to the first switching control node if either the CSMO call indicator or the CSMT call indicator is set;
• and
• initiating routing of the received request message to the second switching control node if neither the CSMO call indicator nor the CSMT call indicator is set.

A proxy operative to handle paging messages for a mobile user equipment (UE) in a mobile communications network, the mobile communications network comprising a first switching control node supporting Circuit Switched Fallback (CSFB) functionality and a second switching control node not supporting the CSFB functionality, the proxy comprising:

• an interface configured to receive a paging response from the UE;
• a control unit configured to:
• identify mobile subscriber identity information and originating signalling point information in the received paging response;
• and
• initiate routing of the received paging response based on the identified information;
• and
• a database containing, for different UEs, mobile subscriber identity information related to originating signalling point information;
• wherein the control unit is further configured to:
• search for mobile subscriber identity information in the database that matches the identified mobile subscriber identity information contained in the paging response;
• initiate routing of the paging response to the second switching control node if matching mobile subscriber identity information is found in the database;
• and
• initiate routing of the paging response to the first switching control node if no matching mobile subscriber identity information is found in the database.

A method implemented by a proxy for handling paging messages for a mobile user equipment (UE) in a mobile communications network, the mobile communications network comprising a first switching control node supporting Circuit Switched Fallback (CSFB) functionality and a second switching control node not supporting the Circuit Switched Fallback (CSFB) functionality, the method comprising:

• receiving a paging response from the UE;
• identifying mobile subscriber identity information and originating signalling point information in the paging response;
• searching for mobile subscriber identity information in a proxy database containing, for different UEs, mobile subscriber identity information related to originating signalling point information, to determine a match for the mobile subscriber identity information contained in the received paging response;
• routing the paging response to the second switching control node if a matching mobile subscriber identity information is found in the database;
• and
• routing the paging response to the first switching control node if no matching mobile subscriber identity information is found in the database.

A proxy operative to handle routing of requests from a mobile user equipment (UE) in a mobile communications network, the mobile communications network comprising a first switching control node supporting Circuit Switched Fallback (CSFB) functionality and a second switching control node not supporting the CSFB functionality, comprising:

• an interface configured to receive a location update request message from the UE including a Temporary Mobile Subscriber Identity Network Resource Identifier (TMSI-NRI) number;
• a database containing a first range of TMSI-NRI numbers, and a second range of TMSI-NRI numbers that are different from the numbers in the first range;
• and
• a control unit configured to:
• identify the TMSI-NRI number included in the location update request message received from the UE;
• initiate routing of the location update request message to the first switching control node if the identified TMSI-NRI number is in the first range;
• and
• initiate routing of the location update request message to the second switching control node if the identified TMSI-NRI number is in the second range.

A method implemented by a proxy for handling routing of requests for a mobile user equipment (UE) in a mobile communications network, the mobile communications network comprising a first switching control node supporting Circuit Switched Fallback (CSFB) functionality and a second switching control node not supporting the CSFB functionality, the proxy containing a database containing a first range of Temporary Mobile Subscriber Identity Network Resource Identifier (TMSI-NRI) numbers, and a second range of TMSI-NRI numbers that are different from the numbers in the first range, the method comprising:

• receiving a location update request message from the UE including a TMSI-NRI number;
• identifying the TMSI-NRI number included in the location update request message;
• routing the location update request message to the first switching control node if the identified TMSI-NRI number is in the first range;
• and
• routing the location update request message to the second switching control node if the identified TMSI-NRI number is in the second range.

A proxy operative to route call-related messages for a mobile user equipment (UE) in a mobile communications network to one of a plurality of switching control nodes, the mobile communications network comprising a first switching control node supporting Circuit Switched Fallback (CSFB) functionality and a second switching control node not supporting the CSFB functionality, the proxy comprising:

• an interface configured to receive a call-related message including a Temporary Mobile Subscriber Identity (TMSI) number;
• a database storing a first range of converted TMSI numbers reserved for the first switching control node, and a second range of converted TMSI numbers that are different from the numbers in the first range, the converted TMSI numbers being stored in a converted space of the database;
• and
• a control unit configured to:
• identify the TMSI number in the call-related message;
• convert the TMSI number of the call-related message into a converted TMSI number of a converted space such that the converted TMSI number is randomly distributed in the converted space;
• route the call-related message to the first switching control node if the converted TMSI number is in the first range;
• and
• route the call-related message to the second switching control node if the converted TMSI number is in the second range.

A method for routing, by a proxy, call-related messages for a mobile user equipment (UE) in a mobile communications network to one of a plurality of switching control nodes, the mobile communications network comprising a first switching control node supporting Circuit Switched Fallback (CSFB) functionality and a second switching control node not supporting the CSFB functionality, the proxy containing a database containing a first range of converted Temporary Mobile Subscriber Identity (TMSI) numbers reserved for the first switching control node, and a second range of converted TMSI numbers different from the numbers in the first range, the method comprising:

• receiving a call-related message including a TMSI number;
• identifying the TMSI number in the call-related message;
• converting the TMSI number into a converted TMSI number of a converted space in such a way that the converted TMSI number is randomly distributed in the converted space;
• routing the call-related message to the first switching control node if the converted TMSI number is in the first range;
• and
• routing the call-related message to the second switching control node if the converted TMSI number is in the second range.

A proxy operative to handle call-related messages for a mobile user equipment (UE) in a mobile communications network, the mobile communications network comprising a first switching control node supporting Circuit Switched Fallback (CSFB) functionality and a second switching control node not supporting the CSFB functionality, the proxy comprising:

• a database containing:
• a first set of Temporary Mobile Subscriber Identity (TMSI) numbers to be used for communication between the proxy and the second switching control node of the mobile communications network, wherein a predefined range of the TMSI numbers of the first set are in a reserved range of TMSI numbers that is reserved for the first switching control node;
• a second set of TMSI numbers to be used for communication between the proxy and the UE;
• and
• a translation table containing an entry for each of the UE whose calls are handled by the second switching control node, the translation table translating a TMSI number of the first set contained in the reserved range to a TMSI number of the second set, and vice versa;
• an interface configured to receive a call-related message including a TMSI number from the second switching control node;
• and
• a control unit configured to:
• identify the TMSI number included in the call-related message transmitted from the second switching control node;
• translate the identified TMSI number in the received message to a TMSI number of the second set based on the translation table, if the identified TMSI number in the call-related message from the second switching control node is in the reserved range of the first set;
• and
• leave the identified TMSI number in the received message untranslated if the TMSI number is not in the reserved range.

A method implemented by a proxy for handling call-related messages for a mobile user equipment (UE) in a mobile communications network, the mobile communications network comprising a first switching control node supporting Circuit Switched Fallback (CSFB) functionality, and a second switching control node not supporting the CSFB functionality, the proxy comprising a database storing a first set and a second set of Temporary Mobile Subscriber Identity (TMSI) numbers, the method comprising:

• receiving a call-related message including a TMSI number from the second switching control node;
• and
• identifying the TMSI number included in the call-related message transmitted from the second switching control node;
• translating the identified TMSI number to a TMSI number of the second set based on a translation table of the database, if the identified TMSI number in the call-related message from the second switching control node is in a reserved range of TMSI numbers of the first set of TMSI numbers;
• and
• leaving the identified TMSI number untranslated if the identified TMSI number is not in the reserved range of the first set of TMSI numbers;
• wherein the first set of TMSI numbers is used for a communication between the proxy and the second switching control node of the mobile communications network;
• wherein the second set of TMSI numbers is used for a communication between the proxy and the UE;
• wherein reserved range of TMSI numbers are reserved for the first switching control node;
• and
• wherein the translation table contains an entry for each of UE whose calls are handled by the second switching control node, the translation table translating a TMSI number of the first set contained in the reserved range to a TMSI number of the second set, and vice versa.

A proxy operative to handle call-related messages for a mobile user equipment (UE) in a mobile communications network, the mobile communications network comprising a first switching control node supporting Circuit Switched Fallback (CSFB) functionality and a second switching control node not supporting the CSFB functionality, the proxy comprising:

• a monitoring unit configured to:
• monitor signalling of traffic of the mobile communications network;
• and
• generate a list of Temporary Mobile Subscriber Identity (TMSI) numbers used by the second switching control node;
• and
• an interface configured to inform the first switching control node of the generated list.

A first switching control node supporting Circuit Switched Fallback (CSFB) functionality for a mobile communications network, wherein the mobile communications network includes a second switching control node not supporting the CSFB functionality, the first switching control node comprising:

• an interface configured to receive a list of Temporary Mobile Subscriber Identity (TMSI) numbers used by the second switching control node, the list being received from a proxy handling call-related messages;
• and
• a control unit configured to:
• generate TMSI numbers for messages of a call controlled by the first switching control node such that the control unit does not generate TMSI numbers contained in the received list;
• and
• if given one of its generated TMSI numbers is determined to be in the list, to change that given TMSI number to a TMSI number that is not included in the list.