I run a SIP phone as well - Fring. Works with Windows, WinMo, Android, iPhone and a bunch of other things, and even is compatible with Skype. It's great to have multiple phone numbers and conferencing on your portable device! Got about 7 phone numbers around the world that ring whatever device I'm currently using (cell phone, tablet, or laptop).
Hopefully wireless carriers "get it" and figure out that the days of making money by selling voice calls is dead, and simply providing connections to the Internet is where the money is at!
I’m running the Bria app. Thanks for the tip on the others.