To VoIP your phone do the following
Note: Make sure your phone is connected to WiFi.
Tap the Phone icon.
Tap the Dialer icon.
**Dial * # * # 8 6 4 7 # * # * (no spaces as shown below by @louisdi
For Samsung phones only, tap the Green Phone icon.
The dialer will disappear. If an activation screen appears, wait for the process to finish, then tap GREAT THANKS!.
The Republic Wireless notification icon may disappear briefly then reappear. If the icon does not reappear after one minute, Restart your phone.
This not something you should need to do very often … you are actually reactivating your phone with RW … you may need to check out your WiFi as something may have gone wrong there.