No sip actions broadcasted after multiple stack start/stop

```

What steps will reproduce the problem?
1. Start the stack, register, stop the stack
2. Repeat several times
3. After some time, the ngn broadcastreceivers are not receiving any actions, I
have put debug breakpoints in the NgnSipService.MySipCallback.OnDialogEvent,
and in fact it was not being fired after several stack restarts

What is the expected output? What do you see instead?
Sip actions should be broadcasted

What version of the product are you using? On what operating system?
latest source from svn imsdroid r554

Please provide any additional information below.
atached a log, that shows the register request is being sent, and no action
being received back, timeout also does not happen
```

Original issue reported on code.google.com by `Sp1n3.t...@gmail.com` on 19 Jul 2013 at 11:56

Attachments:
- [ngnLog.txt](https://storage.googleapis.com/google-code-attachments/imsdroid/issue-464/comment-0/ngnLog.txt)

Start with the attached ngnLog.txt and reproduce repeated stack start, registration, and stop cycles. Trace NgnSipService.MySipCallback.OnDialogEvent and the ngn broadcast receivers; done means SIP actions continue to be broadcast after several restarts and the registration request receives a response or timeout.

Written by the indexing model from the issue text.