Methods and apparatus to support emergency services connectivity requests through untrusted wireless networks

1. A method to request an emergency services connection via an untrusted wireless local area network (WLAN) for a wireless communication device, the method comprising:

by the wireless communication device:

detecting a request for emergency services via the untrusted WLAN;

de-registering from an Internet Protocol Multimedia Subsystem (IMS) server for non-emergency services when the wireless communication device is registered for non-emergency services with the IMS server;

releasing existing packet data network (PDN) connections via the untrusted WLAN;

obtaining an Internet Protocol (IP) address for a first evolved packet data gateway (ePDG);

sending to the first ePDG an IKEv2 CFG_REQUEST message that includes in its configuration payload an indication for emergency services to establish a PDN connection with the first ePDG;

when the first ePDG supports emergency services:

receiving from the first ePDG an IKEv2 CFG_REPLY message that includes in its configuration payload an indication of support for emergency services to establish the PDN connection with the first ePDG; and

establishing the PDN connection with the first ePDG without authentication of the wireless communication device; and

when the first ePDG does not support emergency services:

receiving from the first ePDG a message that includes a second IP address for a second ePDG that supports emergency services;

sending to the second ePDG the IKEv2 CFG_REQUEST message that includes in its configuration payload the indication for emergency services to establish the PDN connection with the second ePDG;

receiving from the second ePDG the IKEv2 CFG_REPLY message that includes in its configuration payload the indication of support for emergency services to establish the PDN connection with the second ePDG; and

establishing the PDN connection with the second ePDG without authentication of the wireless communication device.

2. The method of claim 1 , wherein the request for emergency services is non-specific as to a wireless access network via which to establish the PDN connection, and the method further comprises:

by the wireless communication device:

determining that a cellular service is not available for the wireless communication device to establish the PDN connection for emergency services.

3. The method of claim 1 , wherein the wireless communication device is not authorized to establish a connection via a cellular service in a location at which the wireless communication device is operating.

4. The method of claim 1 , wherein the wireless communication device obtains the IP address for the first ePDG from a stored table that lists IP addresses for ePDGs.

5. The method of claim 1 , wherein the wireless communication device obtains the IP address for the first ePDG by at least:

providing a fully qualified domain name (FQDN) to a domain name system (DNS) server; and

receiving the IP address for the first ePDG from the DNS server.

6. The method of claim 5 , wherein the FQDN does not include a label that indicates that the first ePDG should support emergency services.

7. The method of claim 1 , wherein the IKEv2 CFG_REQUEST message includes a specific configuration attribute assigned for emergency services in its configuration payload.

8. The method of claim 7 , wherein the IKEv2 CFG_REPLY message includes the specific configuration attribute provided by the wireless communication device as part of a set of accepted configuration attributes returned by the first ePDG to the wireless communication device.

9. An apparatus configurable for operation in a wireless communication device, the apparatus comprising:

memory storing instructions; and

processing circuitry comprising one or more processors that, when executing the instructions, cause the wireless communication device to:

detect a request to establish an emergency services connection via an untrusted wireless local area network (WLAN);

de-register from an Internet Protocol Multimedia Subsystem (IMS) server for non-emergency services when the wireless communication device is registered for non-emergency services with the IMS server;

release existing packet data network (PDN) connections via the untrusted WLAN;

obtain an Internet Protocol (IP) address for a first evolved packet data gateway (ePDG);

send to the first ePDG an IKEv2 CFG_REQUEST message that includes in its configuration payload an indication for emergency services to establish a PDN connection with the first ePDG;

when the first ePDG supports emergency services:

receive from the first ePDG an IKEv2 CFG_REPLY message that includes in its configuration payload an indication of support for emergency services to establish the PDN connection with the first ePDG; and

establish the PDN connection with the first ePDG without authentication of the wireless communication device; and

when the first ePDG does not support emergency services:

receive from the first ePDG a message that includes a second IP address for a second ePDG that supports emergency services;

send to the second ePDG the IKEv2 CFG_REQUEST message that includes in its configuration payload the indication for emergency services to establish the PDN connection with the second ePDG;

receive from the second ePDG the IKEv2 CFG_REPLY message that includes in its configuration payload the indication of support for emergency services to establish the PDN connection with the second ePDG; and

establish the PDN connection with the second ePDG without authentication of the wireless communication device.

10. The apparatus of claim 9 , wherein the wireless communication device obtains the IP address for the first ePDG from a stored table that lists IP addresses for ePDGs.

11. The apparatus of claim 9 , wherein the wireless communication device obtains the IP address for the first ePDG by at least:

providing a fully qualified domain name (FQDN) to a domain name system (DNS) server; and

receiving the IP address for the first ePDG from the DNS server.

12. The apparatus of claim 11 , wherein the FQDN does not include an emergency services label as part of the FQDN to indicate that the first ePDG should support emergency services.

13. The apparatus of claim 9 , wherein:

the IKEv2 CFG_REQUEST message includes a specific configuration attribute assigned for emergency services in its configuration payload; and

the IKEv2 CFG_REPLY message includes the specific configuration attribute provided by the wireless communication device as part of a set of accepted configuration attributes returned by the first ePDG to the wireless communication device.

14. A wireless communication device configurable to request an emergency services connection via an untrusted wireless local area network (WLAN), the wireless communication device comprising:

wireless circuitry communicatively coupled to one or more antennas;

one or more processors communicatively coupled to the wireless circuitry; and

a memory communicatively coupled to the one or more processors storing instructions that, when executed by the one or more processors, cause the wireless communication device to:

detect a request to establish the emergency services connection via the untrusted WLAN;

de-register from an Internet Protocol Multimedia Subsystem (IMS) server for non-emergency services when the wireless communication device is registered for non-emergency services with the IMS server;

release existing packet data network (PDN) connections via the untrusted WLAN;

obtain an Internet Protocol (IP) address for a first evolved packet data gateway (ePDG);

send to the first ePDG an IKEv2 CFG_REQUEST message that includes in its configuration payload an indication for emergency services to establish a PDN connection with the first ePDG;

when the first ePDG supports emergency services:

receive from the first ePDG an IKEv2 CFG_REPLY message that includes in its configuration payload an indication of support for emergency services to establish the PDN connection with the first ePDG; and

establish the PDN connection with the first ePDG without authentication of the wireless communication device; and

when the first ePDG does not support emergency services:

receive from the first ePDG a message that includes a second IP address for a second ePDG that supports emergency services;

send to the second ePDG the IKEv2 CFG_REQUEST message that includes in its configuration payload the indication for emergency services to establish the PDN connection with the second ePDG;

receive from the second ePDG the IKEv2 CFG_REPLY message that includes in its configuration payload the indication of support for emergency services to establish the PDN connection with the second ePDG; and

establish the PDN connection with the second ePDG without authentication of the wireless communication device.

15. The wireless communication device of claim 14 , wherein the wireless communication device is not authorized to establish a connection via a cellular service in a location at which the wireless communication device is operating.

16. The wireless communication device of claim 14 , wherein the wireless communication device obtains the IP address for the first ePDG from a stored table that lists IP addresses for ePDGs.

17. The wireless communication device of claim 14 , the wireless communication device obtains the IP address for the first ePDG by at least:

providing a fully qualified domain name (FQDN) to a domain name system (DNS) server; and

receiving the IP address for the first ePDG from the DNS server.

18. The wireless communication device of claim 17 , wherein the FQDN does not include an emergency services label as part of the FQDN to indicate that the first ePDG should support emergency services.

19. The wireless communication device of claim 14 , wherein:

the IKEv2 CFG_REQUEST message includes a specific configuration attribute assigned for emergency services in its configuration payload; and

the IKEv2 CFG_REPLY message includes the specific configuration attribute provided by the wireless communication device as part of a set of accepted configuration attributes returned by the first ePDG to the wireless communication device.