Get SipDroid from the market!! You will have to install Google Voice if you don't already have it. Make sure you have a Google Voice number registered. Tell SipDroid to register a free pbxes account and automatically link to your google voice (there is a button on the bottom for that once you open sipdroid) This is all free stuff. Tell SipDroid to use WiFi and data networks. I recommend you use G722 HD Voice (64kbit) as the audio codec 'cause it works awesomely-fantastical. It also supports video. You now have voice over LTE! I have been using this for a loooong time! The audio clarity is amazing, but can get choppy over wifi. I recommend trying ONLY WiFi, and then ONLY 4g to compare them both. If you don't pay your metro bill, you still have a phone over WiFi!!!