Some comments from users:
"So easy - Just pop in my user name and pass 2 sec later i was making perfect calls. Asus prime was blown away on how simple it was"

"Best google voice app - Better than groove ip in audio quality I have used groove ip for almost a year and this one is way better for my phone and service providers I have a lg optimus v in virgin mobile network"

Spare Phone uses your WiFi,3G,4G data connection to place and receive Google Voice VoIP calls. All you need is the "Spare Phone" app, a data connection(Wireless or Mobile) and a free Google Voice account. Spare Phone transforms your Android phone or tablet into a free wireless phone when used over WiFi/Wireless in the USA and Canada!

Google Voice is currently free to place calls to the U.S. & Canada. Please visit https://www.google.com/voice to create a free Google Voice account and to get your free phone number. Also check out the great rates to other countries such as Mexico and India.

Note: To use 3G, 4G you must enable it in the settings of Spare Phone. This can be costly if you don't have unlimited data. Please verify that your cell carrier allows VoIP data traffic before enabling this option. This app uses ~1.2 MB per minute during a call.

Disclaimers: Google Voice is a product of Google, Inc. and "Spare Phone" is not in any way affiliated or endorsed by Google Inc.
WARNING: Google Voice does not support 911 or any other type of emergency calls!

If you have any suggestions or issues please contact:
androidtouchdev [at] gmail.com

Frequently Asked Questions:

1.) Does this use my cell phone minutes?
Answer: No, Spare Phone uses your wireless/data connection and your Google Voice account for calls. You don't even need cell phone service to use this app. Note: If you are not using WiFi you will pay for your cellular data usage.

2.) Is this a simple callback app?
Answer: No, this is a pure VoIP(Voice over IP) calling app that communicates directly without any additional latency. You DO NOT need a SIP client or callback app to place and receive calls.

3.) Will this work with an Android tablet?
Answer: Yes, Spare Phone will enable your Android tablet to place and receive calls. It will also work with Wi-Fi only tablets too.

4.) I'm not receiving incoming calls. Help!?
Answer: To receive incoming calls you must enable 'Google chat' as one of your phones to ring in the Google Voice settings. Just make sure you don't have the cell phone you're using and 'Google chat' enabled simultaneously.

5.) Calls seem to have issues when my screen turns off.
Answer: In the settings enable 'Keep Screen On' as some devices put the wireless connection to sleep when the screen is off.

6.) I can't login or place calls with my mobile data connection.
Answer: To use 3G,4G you must enable this in the settings. Only wireless is allowed by default. As noted above, mobile data can be costly if you don't have unlimited data. Please verify that your cell carrier allows VoIP data traffic before enabling this option. This application uses ~1.2 MB per minute during a call.

7.) I have some other issue or a suggestion. Help!
Answer: Please email androidtouchdev [at] gmail.com

Thank you for supporting Spare Phone!