Missing ACK when call is established and immediately closed

```
What steps will reproduce the problem?
1. Place a call having ring-back tone generated with Early Media (183 - Session
Progress)
2. The other party sends 200 OK with SDP, immediately followed by a BYE.
3.

What is the expected output? What do you see instead?
Expected: Imsdroid reply with ACK to the 200 OK with SDP and then manage the
incoming BYE message.
Instead: A BYE message is generated from the SIP stack and the call ends with a
"481-Dialog/Transaction Does Not Exists"

What version of the product are you using? On what operating system?
Doubango version 992 and Imsdroid version 554

Please provide any additional information below.
Logcat and Wireshark traces in attach

```

Original issue reported on code.google.com by `massimo....@gmail.com` on 25 Nov 2013 at 3:39

Attachments:
- [Dialog.Connected.and.Terminated.txt](https://storage.googleapis.com/google-code-attachments/imsdroid/issue-495/comment-0/Dialog.Connected.and.Terminated.txt)
- [Dialog.Connected.and.Terminated.pcap](https://storage.googleapis.com/google-code-attachments/imsdroid/issue-495/comment-0/Dialog.Connected.and.Terminated.pcap)