Systems and methods for emergency call route failover

Patent metadata

Field	Value
Publication number	US-9426833-B2
Application number	US-201313783184-A
Country	US
Kind code	B2
Filing date	Mar 1, 2013
Priority date	Mar 1, 2013
Publication date	Aug 23, 2016
Grant date	Aug 23, 2016

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.

First claim

We claim:

1. A computer-implemented method of performing an emergency call route failover within a telecommunications network, the method comprising:
before receiving a Session Initiation Protocol (SIP) request associated with an emergency call, polling each of multiple gateway nodes at a polling interval;
at each polling interval, initiating a SIP OPTION message to each of the multiple gateway nodes;
determining a status of each of the multiple gateway nodes based on the initiated SIP OPTION message; and
based on the determined status, adding or removing one or more gateway nodes from a list of the multiple gateway nodes,
wherein the list provides one or more routing options for the emergency call;

receiving a SIP request associated with the emergency call;
selecting a gateway node from the list of one or more routing options; and
forwarding a SIP request associated with the emergency call to the selected gateway node to provide the emergency call to an emergency network or emergency network node,
wherein the multiple gateway nodes are Media Gateway Control Function (MGCF) nodes when the emergency network has Time Division Multiplex (TDM) connectivity.

2. The method of claim 1 ,
wherein the multiple gateway nodes are Interconnection Border Control Function (IBCF) nodes when the emergency network has Internet Protocol (IP) connectivity.

3. The method of claim 1 , further comprising:
selecting a gateway node from the list of one or more routing options; and
forwarding a SIP request associated with the emergency call to the selected gateway node to provide the emergency call to an emergency network or emergency network node.

4. The method of claim 1 , wherein the determining includes determining a failed status as detected when a gateway node from the multiple gateway nodes provides a response indicating server failure in response to the SIP OPTION message.

5. The method of claim 1 , wherein the determining includes:
determining a failed status as detected when a gateway node from the multiple gateway nodes fails to provide a response to the SIP OPTION message within a predefined amount of time; and,
generating a request timeout error when no response is received from the selected gateway node.

6. The method of claim 1 , wherein the determining includes:
determining a failed status as detected when a gateway node from the multiple gateway nodes fails to provide a response to the SIP OPTION message within a predefined amount of time.

7. The method of claim 6 , further comprising:
failing over to a new gateway node selected from the one or more routing options by sending a SIP request associated with the emergency call to the new gateway node.

8. The method of claim 6 , further comprising:
failing over to a new gateway node selected from the one or more routing options by sending a SIP request associated with the emergency call to the new gateway node,
wherein the one or more routing options are arranged in a specific order, and the new gateway node is selected to load balance distribution of emergency calls among the one or more routing options.

9. At least one non-transitory machine-readable medium storing instruction, which when executed by at least one computer, analyzes nodes for use with emergency call routing in an Internet Protocol Multimedia Subsystem (“IMS”) network, comprising:
before receiving a Session Initiation Protocol (SIP) request associated with an emergency call;
polling each of multiple gateway nodes at a frequency;
based partially on the polling at the frequency, determining a status of each of the multiple gateway nodes;
adjusting a status of one or more gateway nodes in a list of gateway nodes,
wherein the list provides one or more routing options for the received SIP request associated with the emergency call;

initiating a SIP OPTION message towards each of the multiple gateway nodes;
determining a status of each of the multiple gateway nodes based on the initiated SIP OPTION message, and
wherein the list of routing options includes Media Gateway Control Function (MGCF) servers, or Border Gateway Control Function (BGCF) servers which select MGCF servers, or Interconnection Border Control Function (IBCF) servers.

10. The at least one non-transitory machine-readable medium of claim 9 , further comprising:
selecting next routing option from the list of routing options; and
initiating a Session Initiation Protocol (SIP) INVITE request for the emergency call towards the selected routing option.

11. At least one non-transitory machine-readable medium storing instructions, which when executed by at least one machine, causes the at least one machine to:
before receiving a Session Initiation Protocol (SIP) request associated with an emergency call, poll each of multiple gateway nodes at a frequency by initiating a SIP OPTION message towards each of multiple gateway nodes at a frequency;
determine a status of each of the multiple gateway nodes based on the initiated SIP OPTION message initiated at the frequency;
based on the determined status, add or remove one or more gateway nodes from a list of the multiple gateway nodes,
wherein the list provides one or more routing options for the received SIP request associated with the emergency call;

select a gateway node from the list of one or more routing options; and
forward a SIP request associated with the emergency call to the selected gateway node to provide the emergency call to an emergency network or emergency network node,
wherein the multiple gateway nodes are Interconnection Border Control Function (IBCF) nodes when the emergency network has Internet Protocol (IP) connectivity.

12. The at least one non-transitory machine-readable medium of claim 11 , storing instructions, which when further executed by the at least one machine, causes the at least one machine to:
wherein the multiple gateway nodes are Media Gateway Control Function (MGCF) nodes when the emergency network has Time Division Multiplex (TDM) connectivity.

13. The at least one non-transitory machine-readable medium of claim 11 , storing instructions, which when further executed by the at least one machine, causes the at least one machine to:
select a gateway node from the list of one or more routing options; and
forward a SIP request associated with the emergency call to the selected gateway node to provide the emergency call to an emergency network or emergency network node.

14. The at least one non-transitory machine-readable medium of claim 11 , wherein the instructions when executed cause the at least one machine to determine a failed status as detected when a gateway node from the multiple gateway nodes provides a response indicating server failure in response to the SIP OPTION message.

15. The at least one non-transitory machine-readable medium of claim 11 , wherein determine the status the instructions when executed cause the at least one machine to:
determine a failed status as detected when a gateway node from the multiple gateway nodes fails to provide a response to the SIP OPTION message within a predefined amount of time; and,
generate a request timeout error when no response is received from the selected gateway node.

16. The at least one non-transitory machine-readable medium of claim 11 , wherein to determine the status includes determining a failed status as detected when a gateway node from the multiple gateway nodes fails to provide a response to the SIP OPTION message within a predefined amount of time.

17. The at least one non-transitory machine-readable medium of

Assignees

• T Mobile Usa Inc

Inventors

• Mufti Shujaur Rehman
• Hooker William Michael

Classifications

• H04L65/1016 Primary

  IP multimedia subsystem [IMS] · CPC title

• H04W4/90

  Services for handling of emergency or hazardous situations, e.g. earthquake and tsunami warning systems [ETWS] · CPC title

• H04W76/50

  for emergency connections · CPC title

• H04L65/1046

  Call controllers; Call servers · CPC title

• H04W80/04

  Network layer protocols, e.g. mobile IP [Internet Protocol] · CPC title