A lot of people have been asking if it would be possible to use the Nexus 7 as a phone. The answer is yes, and you can do it with a simple installation of an app. Via VoIP, you can use the Nexus 7 for both outgoing and incoming calls.
To do it,
just install the GrooVe IP Lite app via Google Play. You don’t need to purchase the full version since the only difference is that the full version is usable even if you are using 3G or 4G web connection rather than WIFI.
When running GrooVe IP Lite for the first time, it will ask for your Google Voice login credentials. If you still don’t have a Google Voice, you can get one for free.
After the initial setup, you should be able to use your tablet to make calls.
If you want to forward Google Voice incoming calls to your Nexus 7, make sure to check the “Forwards calls to: Google chat” check box on the Google Voice settings.