So I got a trial account setup at Onsip and have tried getting this to work in both Fring and the native SIP application. Fring doesn't acept the credentials (Onsip has a kind of funky way to enter in everything if you are using Fring, and the only comments are from people on multiple platforms that can't get it to work, so that's not totally surprising). The native SIP client in the phone seems to take the credentials fine and says I've logged in...but I don't know how to actually make it try and use that account? If I try to do a test call it just tells me that I don't have a SIM. Which is true, but I'm connected to Wifi, and my understanding is this should work with data, it just seems like it is trying to use the cell phone client instead. Feel like I'm missing something obvious here.

BTW, this was originally meant to be posted in the N900 section, didn't mean for it to go in General. If a mod would like to move it there (or another forum that is more appropriate) that's fine with me. Sorry for my mistake.