Method and apparatus for a mobile station to enhance the probability of successful emergency call completion and successful callback from emergency service centre

1. A method of enhancing the probability of a successful emergency call completion on a mobile station in a network, comprising:

during an emergency call attempt by a mobile station, determining whether the mobile station is engaged in one or more data communication sessions with the network;

if the mobile station is engaged in one or more data communication sessions:

terminating the one or more data communication sessions;

attempting to acquire a network of the one or more data communication sessions for the emergency voice call;

if the attempting to acquire the network of the one or more data communication sessions failed, attempting to acquire a different network for the emergency call;

if the mobile station is not engaged in one or more data communication sessions, attempting to acquire a network for the emergency call.

2. The method of claim 1 , further comprising the steps of: if said one or more data communication sessions with the network is ended, attempting to acquire a network for the emergency call attempt.

3. The method of claim 2 , wherein said step of attempting to acquire a network includes periodically attempting to reacquire said network that communication was ended with.

4. The method of claim 1 , wherein the mobile station is allowed to acquire any network regardless of whether the network is preferred.

5. The method of claim 4 , wherein said mobile station can acquire a network even if a subscriber identity module or a removable user identity module is not present.

6. The method of claim 1 , further comprising the steps of: sending an emergency call request to the network; checking whether the emergency call request was successful; if said emergency call request was unsuccessful, checking whether the user aborted the emergency call request; and if said user did not abort said emergency call request, attempting to acquire a new system.

7. The method of claim 1 , including: during a callback period, monitoring whether the mobile station has received a service request from the network and, if yes, ignoring said service request if said service request is a non-voice service request that is anything but a position location service request, said step of ignoring said service request includes blocking sending of an acknowledgement message generated by the mobile station based on said non-voice service request.

8. The method of claim 7 , wherein said method further includes the steps of: setting up a call for a voice service request or a non-voice position location service request; ending said call; checking whether a callback timer has expired, and if so entering a regular mode.

9. A mobile station for enhancing the probability of successful emergency call completion to a network and successful callback from emergency service center, the mobile station comprising:

a communications subsystem, said communications subsystem including a receiver, a transmitter and a digital signal processor;

a microprocessor communicating with said digital signal processor of said communications subsystem;

user input and output means communicating with said microprocessor;

memory communicating with said microprocessor; and

an emergency service module, said emergency service module communicating with both said digital signal processor and said microprocessor, wherein

during an emergency call attempt or callback said emergency service module directs said microprocessor for determining whether the mobile station is engaged in one or more data communication sessions with the network;

if the mobile station is engaged in one or more data communication sessions:

terminating the one or more data communication sessions;

attempting to acquire a network of the one or more data communication sessions for the emergency voice call;

if the attempting to acquire the network of the one or more data communications sessions failed, attempting to acquire a different network for the emergency call;

if the mobile device is not engaged in one or more data communication sessions, attempting to acquire a network for the emergency call.

10. The mobile station of claim 9 , wherein said emergency service module further directs said microprocessor to block any user initiated, non-position location service requests from a user during a callback period.

11. The mobile station of claim 9 , further comprising a subscriber identity module/removable user identity module interface.

12. The mobile station of claim 10 , wherein said mobile station can acquire a network during an emergency call attempt without a subscriber identity module or a removable user identity module present in said subscriber identity module/removable user identity module interface.