Systems and methods for emergency call route failover

At least one machine-readable medium, excluding transitory signals, having stored thereon instructions, which when executed by at least one processor, performs an emergency call route failover within a telecommunications network by causing an Emergency Call Session Control Function (E-CSCF) executed by the processor to:

• receive a Session Initiation Protocol (SIP) INVITE request associated with an emergency call;
• obtain an Emergency Service Routing Key (ESRK) number associated with the emergency call;
• when the ESRK number is in a range accessed by the E-CSCF and when a translated number is associated with the ESRK number:
• select an Interconnection Border Control Function (IBCF) server or a Session Border Controller (SBC) server from a peer nodes list;
• modify the SIP INVITE request to include the translated number;
• forward the SIP INVITE request to the selected IBCF server or the selected SBC server based on the translated number for routing to a Public-Safety Answering Point (PSAP) associated with the translated number;
• when the ESRK number is in a range accessed by the E-CSCF and when a translated number is not associated with the ESRK number:
• select a Border Gateway Control Function (BGCF) server or a Media Gateway Control Function (MGCF) server from a peer nodes list;
• modify the SIP INVITE request to include the ESRK number;
• and
• forward the SIP INVITE request to the selected BGCF server or the selected MGCF server based on the translated number for routing to a Public-Safety Answering Point (PSAP) associated with the ESRK number.

A computer-implemented method performed at an Emergency Call Session Control Function (E-CSCF) for performing an emergency call route failover within a telecommunications network, the method comprising:

• receiving a Session Initiation Protocol (SIP) INVITE request associated with an emergency call;
• obtaining an Emergency Service Routing Key (ESRK) number associated with the emergency call;
• when the ESRK number is in a range accessed by the E-CSCF and when a translated number is associated with the ESRK number:
• selecting an Interconnection Border Control Function (IBCF) server or a Session Border Controller (SBC) server from a peer nodes list;
• modifying the SIP INVITE request to include the translated number;
• forwarding the SIP INVITE request to the selected IBCF server or the selected SBC server based on the translated number for routing to a Public-Safety Answering Point (PSAP) associated with the translated number;
• when the ESRK number is in a range accessed by the E-CSCF and when a translated number is not associated with the ESRK number:
• selecting a Border Gateway Control Function (BGCF) server or a Media Gateway Control Function (MGCF) server from a peer nodes list;
• modifying the SIP INVITE request to include the ESRK number;
• and
• forwarding the SIP INVITE request to the selected BGCF server or the selected MGCF server based on the translated number for routing to a Public-Safety Answering Point (PSAP) associated with the ESRK number.