Geographic redundancy for call servers in a cellular system based on a bearer-independent core network

A signaling gateway for coupling to a plurality of network elements, the signaling gateway comprising:

• at least one processor configured to execute processor-executable instructions causing the at least one processor to:
• store information identifying one or more backup network elements for each of a plurality of primary network elements;
• and
• store the processor-executable instructions that define operational logic of the signaling gateway, the processor-executable instructions further causing the at least one processor to:
• monitor a heartbeat signal from a first primary network element of the plurality of primary network elements;
• determine whether the first primary network element of the plurality of primary network elements is in an inactive state;
• when the first primary network element is in an inactive state, determine from the stored information identifying the one or more backup network elements, a first backup network element corresponding to the first primary network element;
• receive call signaling messages from a second primary network element of the plurality of primary network elements;
• forward the call signaling messages to the first backup network element by encapsulating the call signaling messages in data packets with a destination address of the first backup network element;
• monitor heartbeat signals from the first backup network element;
• when the first backup network element is in an inactive state, determine from the stored information a second backup network element corresponding to the first primary network element;
• and
• forward the call signaling messages to the second backup network element by encapsulating the signaling messages in data packets with a destination address of the second backup network element.

A method of transferring call control to a backup call server, the method comprising:

• storing information identifying at least one backup call server for a primary call server;
• monitoring the primary call server to determine an active or inactive state of the primary call server;
• determining an inactive state for the primary call server;
• responsive to the inactive state determination, forwarding signaling messages from a signaling gateway to the at least one backup call server by encapsulating the signaling messages in at least one data packet having a destination address of the at least one backup call server based upon the stored information;
• monitoring heartbeat signals from a first backup call server of the at least one backup call server;
• when the first backup call server is in an inactive state, determining, from the stored information, another backup call server corresponding to the first backup call server;
• and
• forwarding the call signaling messages to the another backup call server by encapsulating the signaling messages in data packets with destination address of the another backup call server.

A method of transferring call control to a backup call server, the method comprising:

• storing information identifying at least one backup call server for a primary call server;
• monitoring the primary call server to determine an active or inactive state of the primary call server;
• determining an inactive state for the primary call server;
• responsive to the inactive state determination, forwarding signaling messages from a signaling gateway to the at least one backup call server by encapsulating the signaling messages in at least one data packet having a destination address of the at least one backup call server based upon the stored information;
• replicating data of the primary call server in the at least one backup call server;
• designating as active the replicated data in the at least one backup call server when the primary call server is in an inactive state.