Dear Jitusj
Fyi, on N900 action Voip settings as below on setting

address : UN@voiparound.com
PW
Enabled - Click
Advance setting : actionvoip - UN
transport : UDP
Port : 5060
Discover pub add : click
loose rout : click
mechanism : alive
period : alive
Auto dect stun : Click
Done - Save
You will suceed, Let me know
Rgds/Rabi