Thanks for the reply, but that doesn't have any effect on the connection. The N900 doesn't reach to connect with the SIP Service. Error is: "Network error". Is there a log file, which gives me further details on connection errors?

For the S60 3rd Edition Phones it works with the following configuration:

Service profile: IETF
Public address: h1xxxxxxx_x@ssl2.telefon.unitymedia.de
Use compression: No
Use security mechanism: No

Proxyserver
Proxyserver-Address: sip:ssl2.telefon.unitymedia.de
Region: none
User Name: h1xxxxxxx_x
Loose Routing: Yes
Transport: Auto
Port: 5060

Registrationserver
Registrationserver-Address: sip:ssl2.telefon.unitymedia.de
Region: Realm
User Name: h1xxxxxxx_x
Transport: UDP
Port: 5060

Is there a way to put this config into the N900? Maybe via a config file which allows advanced sip configuration.

Greets
Vinc