Taken from: http://www.entropyfarm.org/things/google-voice-setup-t-mobile/
As with other things on this site, I’m lazy and hate to run into a problem that requries hours of digging through forum posts for a solution. The following is (probably) what you should do if:
- You are on T-Mobile in the USA
- You have an Android phone (this may work with others but I have no idea)
- You have a Google Voice number with voicemail set up already
- You want to use Google Voice as your voicemail instead of T-Mobile’s VM
Setup
If all of the above apply to you, the solution is fairly simple:
- In a browser, login to your Google Voice account, and click on Settings. In the Voicemail tab, set up your greeting.
- On your phone, install the Google Voice App.
- From your phone’s dialer, enter * * 0 0 4 * [Your Google Voice Number] #
That’s it, pretty simple.
To disable forwarding, again from your dialer, dial: # # 0 0 4 #


