For those who can't use T-mobile for porting, here's my experience with AT&T:
My landline showed as not port-able with T-Mobile, but when I checked with AT&T, they could do it. It was explained to me that it had something to do with control of cell towers in my area (east central WI) -- apparently, T-Mobile doesn't have any towers in my area.
I stopped by an AT&T store and explained what I wanted to do. The agent there set me up with a prepaid SIM -- didn't charge me for it. It had a zero balance, but was set up with my landline number. I brought along a phone bill from my landline carrier so he could verify the account information. He then initiated the port process from my landline carrier to AT&T.
I then went to WalMart and bought a $15 GoPhone so I could insert this SIM. When I inserted the SIM, I noticed that my landline phone number came up but was still inactive since the porting hadn't gone through. Using the landline #, I was able to log in to att.com
and confirm the account the agent had set up earlier. At that time, I added some money to the prepaid account. To check the status of the porting, I logged into att.com/port
, input the phone number and it reported date and time when the port was expected to be complete.
When the port from landline to cellphone was complete, I received a message on the GoPhone and also tested calls out and in to the GoPhone. I then logged into Google Voice and initiated the port process from AT&T to GV. NOTE: at first I tried entering the cellphone (my old landline) # as the account number for the porting process on GV, since I used that number to log into my account with AT&T. But GV kept kicking back an error with an invalid account number. I ended up calling AT&T customer service and asking for an account number. Sure enough, there was an account number tied to the account that didn't show up online when I was logged into "myAT&T". With that account number, the porting request with GV went through.
In retrospect, I probably could have just bought a GoPhone to begin with and initiated a port of my landline with the setup of the GoPhone, but I went the route of stopping by my local AT&T store first and the agent took it from there.
Hope this helps someone whose number is won't port through T-Mobile.