Generic SIP phone intermittent registration issues 3300

[rees]

We've got a Biamp TesiaForte SIP client configured as a Generic SIP phone which is randomly losing registration and sometimes having major issues re-registering to the server.

I've taken a SIP dump from the server and while the Generic SIP phone (10.60.172.241) seems pretty normal, there are a tonne of "500 Server Internal Error" coming from 10.60.1.102 which is apparently the Mitel MyCollab Server. Is this normal? OR could it be adversely affecting other connections.

I've attached the SIP dump.

Any help would be much appreciated 

[petr.necas]

I'm not sure about MiCollab but on MCD when trying to register unknown user it returns 404 Not Found with a reason but on the next attempt it returns 500 Server Internal Error.  Maybe if you restart the MiCollab and sniff the first registration request it may give you a more detailed info.