I've been reading all the treads about this issue but I haven't got any clear conclusion. I've been making voip calls between two N80 phones in the same subnet using Asterisk and also different SIP proxies and it worked fine over Wifi.
Next step is trying it over 3G. I've read that it is not possible on N80, but in some other posts it is said that it is possible but difficult to get. I really need to make it work over 3G, so, please, can anybody tell me what I need to do?

I guess it is not enough with setting the profile to 'Nokia 3gpp' instead of 'IETF'.
In the SIP VOIP Setting application->VOIP services->profile settings->allow voip over WCDMA, the default value is 'OFF' so I guess it should be 'ON' for 3G, am I right?

Those are the 2 changes I think they need to be done to make it work on 3G, BUT, is that enough??? Do I need to go deeper and program my own voip client? (I hope not because I cant program...)