Registration issue

Hello

We've seen the following issue in our customer's network.

 

When an UA registers for the first time, everything goes well (register->unath->register->200OK).
If I turn off my UA it will nicely de-register by sending a REGISTER with expires=0. So when I register again after a couple of seconds (in this case approx 20 seconds) the following happens:


UA sends register:
From: "first.lastname" <sip:first.lastname@mydomain.com>;tag=xyz


After successful authentication the registrar sends the 200 OK with 2 bindings, whereby the top binding is the 'old' registration:

Contact: <sip:first.lastname-kr1r18uh2hibf@85.110.67.23:5060;transport=udp>;expires=1143