That's good to know the version of Sipdroid in market is fully functional now. The app is allot more solid since the 1.4.7 release.

I route all calls through either my free Gizmo5 (not accepting new accounts at the moment) or free Sipgate accounts and then into Google Voice for the outgoing hop onto the POTS network. The trick is to use the free site sipsorcery.com to run a script on outgoing calls to transparently trick Google Voice into thinking it is doing a callback on outgoing calls. It is completely transparent in operation. I dial someones ordinary US number, it rings showing my Google Voice number as caller ID. No callback app or anything. Just Sipdroid. Although not technically necessary I also route outbound calls through a free account at pbxes.org en-route to sipsorcery.com. This has increased reliability dramatically and solves some issues with ISP's blocking VOIP.

It is crazy difficult to set up. Intensely complicated and needed allot of tweaking, and trying different codecs and such to get it all working smothely. But it works and now all calls through Sipgate, both incoming AND outgoing to USA are 100% completely free Google Voice calls. Completely transparently.

There are good write ups on the system here but it may still need a fair amount of tweeking to get it all strait.

http://docs.google.com/Doc?docid=0Ae...M4ZjNjeA&hl=en
http://forum.xda-developers.com/showthread.php?t=548405

If you enjoy a difficult technical challenge as a game like a puzzle, to keep your thinking sharp, it really is a super cool setup. If you are looking for free phone calls with no effort on the set-up, better to pay a SIP providers nominal service fee.