Setting up Nokia mobiles tends to be tricky business...
There is a long thread
http://forum.voxalot.com/voxalot-sup...a-support.html dedicated to the Nokia setup
Scenario 1: Everything tends to work fine with the original Nokia App
Scenario 2: You need to download an extra App from Nokia which allows you more fields to setup such as STUN seetings .
See
Nokia Configuration Settings - Voxalot FAQ about SipVoipSettings .sis application from Nokia
Scenario 3: Try installing Fring(
fring – Make free mobile calls, IM with Skype, MSN Messenger, ICQ, Google Talk™, SIP & Twitter, AIM® & Yahoo!™) (if supported by your device) then configure VoXalot with Fring.