You can find SipDroid here:http://sipdroid.com/It works quite nicely, even running as a service and waiting for calls. Here's a video of my m001 receiving a phone call:http://video.yahoo.com/watch/7572559/20078715SIP is a standard used in VoIP and this app should work with any SIP provider that permits softphones and/or your own device. I use sipgate.com, but there are plenty of options. You'll need to turn the volume to max if you're using the internal speaker (not recommended, due to echo) but it works with earphones/build in mic.