| How to authorize an old GVoice number that was ported to T-Mobile to be a forwarding number to another Gvoice acct | TIkboy | 6/9/12 12:30 PM | I recently ported my other Google Voice number to T-Mobile, it was successful. I have another Google Voice number which I've been using for a long time. I wanted to make the ported number to T-Mobile as a forwarding number but I always get a message |