Methods and apparatus to maintain call continuity

1. A user equipment (UE) configured to:

initiate a tracking area updating (TAU) procedure in an evolved packet system (EPS) mobility management (EMM) connected (EMM_CONNECTED) mode;

identify a lack of a voice service in response to the TAU procedure being successful;

identify a bearer context; and

stay in the EMM_CONNECTED mode until a radio bearer associated with the bearer context are released.

2. A UE as defined in claim 1 , further configured to locally release an established non-access stratum signaling connection in response to the release of the bearer context.

3. A UE as defined in claim 1 , wherein the bearer context comprises an evolved packet system bearer context.

4. A UE as defined in claim 1 , wherein the bearer context comprises a target quality of service control index of 1.

5. A method comprising:

initiating, at a user equipment (UE), a tracking area updating (TAU) procedure in an evolved packet system (EPS) mobility management (EMM) connected (EMM_CONNECTED) mode;

receiving a TAU ACCEPT message;

identifying a lack of a voice service in response to receiving the TAU ACCEPT message;

identifying a bearer context; and

refraining from releasing the bearer context until a radio bearer associated with the bearer context is released.

6. A method as defined in claim 5 , further comprising the UE locally releasing an established non-access stratum signaling connection in response to the release of the radio bearer.

7. A method as defined in claim 6 , further comprising entering an evolved packet system mobility management (EMM) IDLE mode before selecting one of (a) a global system for mobile communication (GSM) radio access network (GERAN) radio access technology or (b) a universal terrestrial radio access network (UTRAN) radio access technology.

8. A method as defined in claim 5 , wherein the bearer context is a bearer context of interest.

9. A method as defined in claim 8 , wherein the bearer context of interest is an EPS bearer context.

10. A method as defined in claim 8 , wherein the bearer context of interest comprises a target quality of service control index value of 1.

11. A method as defined in claim 5 , wherein the UE is in circuit switched/packet switched (CS/PS) mode 1.

12. A method as defined in claim 5 , wherein the TAU ACCEPT message comprises an evolved packet system mobility management (EMM) cause value.

13. A method as defined in claim 12 , wherein the EMM cause value comprises one of #22 and #18.

14. A method as defined in claim 5 , wherein a tracking area updating timer is equal to 5.

15. A method as defined in claim 5 , wherein the bearer context comprises an emergency bearer context.

16. A method as defined in claim 5 , wherein identifying the lack of a voice service is indicative of Internet Protocol multimedia subsystem (IMS) voice not available.

17. A user equipment (UE), configured to:

initiate a tracking area updating (TAU) procedure in an evolved packet system (EPS) mobility management (EMM) connected (EMM_CONNECTED) mode;

receive a TAU ACCEPT message;

identify a lack of a voice service in response to receiving the TAU ACCEPT message;

identify a bearer context; and

refrain from releasing the bearer context until a radio bearer associated with the bearer context is released.

18. A UE as defined in claim 17 , further configured to locally release an established non-access stratum signaling connection in response to the release of the radio bearer.

19. A UE as defined in claim 18 , further configured to enter an EMM-IDLE mode before selecting one of (a) a global system for mobile communication (GSM) radio access network (GERAN) radio access technology or (b) a universal terrestrial radio access network (UTRAN) radio access technology.

20. A UE as defined in claim 17 , wherein the bearer context is a bearer context of interest.

21. A UE as defined in claim 20 , wherein the bearer context of interest is an evolved packet system bearer context.

22. A UE as defined in claim 20 , wherein the bearer context of interest comprises a target quality of service control index value of 1.

23. A UE as defined in claim 17 , wherein the UE is in circuit switched/packet switched (CS/PS) mode 1.

24. A UE as defined in claim 17 , wherein the TAU ACCEPT message comprises an EMM cause value.

25. A UE as defined in claim 24 , wherein the EMM cause value comprises one of #22 and #18.

26. A UE as defined in claim 17 , wherein a tracking area updating timer is equal to 5.

27. A UE as defined in claim 17 , wherein the bearer context comprises an emergency bearer context.

28. A UE as defined in claim 17 , further configured to identify the lack of a voice service is indicative of Internet Protocol multimedia subsystem (IMS) voice is not available.