Emergency call prioritization

1. A method of operating a communication system, the method comprising:

receiving a first user request from a communication device for a voice service;

in response to receiving the first user request, transferring an initial message requesting access to the voice service;

receiving a response to the initial message that indicates that the voice service is not available;

after receiving the response, receiving a second user request from the communication device;

processing the second user request to determine if the second user request indicates an emergency service;

if the second user request indicates the emergency service, then transferring a call request for the emergency service, wherein the call request comprises an out-of-sequence notification message that indicates a high priority of the call request; and

if the second user request does not indicate the emergency service, then notifying the communication device that the voice service is not available.

2. The method of claim 1 wherein the first user request comprises, in the communication device, enabling a data transmission for a communication link.

3. The method of claim 1 wherein transferring the initial message requesting access to the voice service comprises transferring an off-hook notify.

4. The method of claim 1 wherein receiving the second user request comprises receiving dialed digits from the communication device.

5. The method of claim 4 wherein processing the second user request to determine if the second user request indicates the emergency service comprises processing the second user request to determine if the dialed digits are equal to 9-1-1.

6. The method of claim 1 wherein receiving the response to the initial message comprises receiving a Negative Acknowledgement (NACK) from a call control system due to network congestion.

7. The method of claim 6 further comprising:

in the call control system, receiving the call request, processing the call request to determine that the call request comprises the out-of-sequence notification message that indicates the high priority of the call request, and transferring the call request to a communication server.

8. The method of claim 1 wherein transferring the call request for the emergency service comprises transferring a call request comprising a priority bit.

9. The method of claim 8 wherein the priority bit indicates that the dialed digits are equal to 9-1-1.

10. The method of claim 1 further comprising:

in response to transferring the call request for the emergency service, receiving a successful response from a call control system; and

connecting the communication device to an emergency service.

11. A communication system comprising:

a communication interface configured to:

receive a first user request from a communication device for a voice service;

in response to receiving the first user request, transfer an initial message requesting access to the voice service;

receive a response to the initial message that indicates that the voice service is not available;

after receiving the response, receive a second user request from the communication device; and,

a processing system configured to:

process the second user request to determine if the second user request indicates an emergency service;

if the second user request indicates the emergency service, then the communication interface configured to transfer a call request for the emergency service, wherein the call request comprises an out-of-sequence notification message that indicates a high priority of the call request; and

if the second user request does not indicate the emergency service, then the communication interface configured to notify the communication device that the voice service is not available.

12. The system of claim 11 wherein the first user request comprises, in the communication device, the enablement of a data transmission for a communication link.

13. The system of claim 11 wherein the initial message requesting access to the voice service comprises an off-hook notify.

14. The system of claim 11 wherein the second user request comprises dialed digits from the communication device.

15. The system of claim 14 wherein the dialed digits are equal to 9-1-1.

16. The system of claim 11 wherein the response to the initial message comprises a Negative Acknowledgement (NACK) from a call control system due to network congestion.

17. The system of claim 16 further comprising:

the call control system configured to receive the call request, process the call request to determine that the call request comprises the out-of-sequence notification message that indicates the high priority of the call request, and transfer the call request to a communication server.

18. The system of claim 11 wherein the call request for the emergency service comprises a priority bit.

19. The system of claim 18 wherein the priority bit indicates that the dialed digits are equal to 9-1-1.

20. The system of claim 11 further comprising:

in response to transferring the call request for the emergency service, the communication interface configured to receive a successful response from a call control system; and

the processing system configured to connect the communication device to an emergency service.