Systems and methods for emergency call route failover

• US 10,219,171 B2
• Filed: 04/05/2018
• Issued: 02/26/2019
• Est. Priority Date: 03/01/2013
• Status: Active Grant

• Current Assignee: T-Mobile USA, Inc. (Deutsche Telekom AG)
• Original Assignee: T-Mobile USA, Inc. (Deutsche Telekom AG)
• Inventors: Mufti, Shujaur Rehman, Hooker, William Michael
• Primary Examiner(s): Fang, Pakee
• Application Number:
  US15/946,698
• Publication Number:
  US 20180227778A1
• Time in Patent Office: 327 Days
• CPC Class Codes: H04L 65/1016 IP multimedia subsystem [IMS]
• CPC Class Codes: H04L 65/1046 Call controllers; Call servers
• CPC Class Codes: H04L 65/1069 Session establishment or de-establishment
• CPC Class Codes: H04W 24/04 Arrangements for maintaining operational condition
• CPC Class Codes: H04W 4/90 Services for handling of emergency or hazardous situations, e.g. earthquake and tsunami warning systems [ETWS]
• CPC Class Codes: H04W 76/10 Connection setup
• CPC Class Codes: H04W 76/50 for emergency connections
• CPC Class Codes: H04W 80/04 Network layer protocols, e.g. mobile IP [Internet Protocol]
• CPC Class Codes: H04W 88/16 Gateway arrangements

Abstract

A system and method for performing an emergency call route failover between an Emergency Call Session Control Function (E-CSCF) and multi-homed remote end-point functions such as Border Gateway Control Function(BGCF)/Media Gateway Control Function (MGCF) or Interconnection Border Control Function (IBCF) in an Internet Protocol Multimedia Subsystem (IMS) uses Session Initiation Protocol (SIP) and/or Domain Name System (DNS) methods. The E-CSCF and/or a DNS server monitors the availability of the remote end-points to create a peer list of route options. The E-CSCF or the DNS server selects a route option from the peer list to route an emergency call to an appropriate Public Safety Answering Point (PSAP). In the event that the route option fails, the E-CSCF fails over to the next available route option to route the emergency call.

Claims

1. A system for performing an emergency call route failover within a telecommunications network, comprising:

at least one processor;

an Emergency Call Session Control Function (E-CSCF) executed by the processor and configured for;

receiving a Session initiation Protocol (SIP) INVITE request associated with an emergency call;

obtaining an Emergency Service Routing Key (ESRK) number or Public Switched Telephone Network (PSTN) 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.

2. The system of claim 1, wherein the ESRK number is a routing key or a phase 0 PSTN number.

3. The system of claim 1, wherein the ESRK number is in a range associated with a particular public safety organization.

4. The system of claim 1, wherein the ESRK number is used by a receiving Public-Safety Answering Point (PSAP) to obtain one of more of the following information:

location, coordinates, ownership, or any combination thereof.

5. The system of claim 1, wherein the E-CSCF is further configured to:

when the ESRK number is not in a range accessed by the E-CSCF;

identify the emergency call as a phase 0 call; and

route the SIP INVITE request via the PSTN to a Public-Safety Answering Point (PSAP).

6. The system of claim 1, wherein when the ESRK number is not in a range accessed by the E-CSCF, the E-CSCF is further configured to:

select a Media Gateway Control Function (MGCF) node from a peer list of MGCF nodes; and

modify the SIP INVITE request to include the PSTN number in a request-URI.

7. The system of claim 1, wherein an IBCF identifier identifying the IBCF server is included in a routing header of the SIP INVITE request as a hop in a path of the emergency call.

8. The system of claim 1, the E-CSCF is further configured to initiate a SIP OPTION message towards each of one or more gateway nodes at a preconfigured frequency to monitor the status of each of the one or more gateway nodes.

9. 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.

10. The at least one machine-readable medium of claim 9, wherein the ESRK number is a routing key or a phase 0 Public Switched Telephone Network (PSTN) number.

11. The at least one machine-readable medium of claim 9, wherein the ESRK number is in a range associated with a particular public safety organization.

12. The at least one machine-readable medium of claim 9, wherein the ESRK number is used by a receiving Public-Safety Answering Point (PSAP) to obtain one of more of the following information:

location, coordinates, ownership, or any combination thereof.

13. The at least one machine-readable medium of claim 9, wherein when the ESRK number is not in a range accessed by the E-CSCF, the E-CSCF is further configured to:

identify the emergency call as a phase 0 call; and

route the SIP INVITE request via a Public Switched Telephone Network (PSTN) to a Public-Safety Answering Point (PSAP).

14. The at least one machine-readable medium of claim 9, wherein when the ESRK number is not in a range accessed by the E-CSCF, the E-CSCF is further configured to:

select a Media Gateway Control Function (MGCF) node from a peer list of MGCF nodes; and

modify the SIP INVITE request to include a Public Switched Telephone Network (PSTN) number in a request-URI.

15. The at least one machine-readable medium of claim 9, wherein an IBCF identifier identifying the IBCF server is included in a routing header of the SIP INVITE request as a hop in a path of the emergency call.

16. The at least one machine-readable medium of claim 9, wherein the E-CSCF is further configured to initiate a SIP OPTION message towards each of one or more gateway nodes at a preconfigured frequency to monitor the status of each of the one or more gateway nodes.

17. 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.

18. The method claim 17, wherein when the ESRK number is not in a range accessed by the E-CSCF, the method further comprises:

selecting a Media Gateway Control Function (MGCF) node from a peer list of MGCF nodes; and

modifying the SIP INVITE request to include a Public Switched Telephone Network (PSTN) number in a request-URI.

19. The method claim 17, wherein an IBCF identifier identifying the IBCF server is included in a routing header of the SIP INVITE request as a hop in a path of the emergency call.

20. The method claim 17, further comprising initiating a SIP OPTION message towards each of one or more gateway nodes at a preconfigured frequency to monitor the status of each of the one or more gateway nodes.