Remove register callback and check registration state via cli when offhook

Code changes to remove the callback check for registration, Instead using the CLI to check the register state.

The test cases executed are : 1- Caller A calls Callee B Result: Call success 2- Caller A calls Callee B ,B Is Busy Result: A Gets a busy tone, Success 3- Caller A call Invalid Number Result: get congestion /busy tone, Success 4- Caller A calls B ,B picks,B holds the call ,B unhold ,B terminate Result: Call success 5- Caler A calls B,B holds and adds C ,B press 3 and all three party are in call Result: Call success 6- Caller B dials 21c# ,A calls B ,call goes to C Result: Call success 7- From Juci Add a subscriber Result: Dial tone is heard once it's registered, Success 8- From Juci Add an invalid subscriber Result: No dial tone,Success 9- From Juci Delete a valid subscriber Result: No dial tone, Success 10- Delete an invalid valid subscriber Result: No dial tone, Success 11- Reload brcm with valid subscriber Result: Dial tone is heard, Success 12- Add a valid user,reboot the dut Result: dial tone on reboot complete, Success 13- User re-registers after the register expires Result: Dial tone present, Success 14- Add a valid number, tone should be heard.Make the subsequent register fail-No dial tone , Success