Our newly unlocked T-Mobile G1 Google Android phone

The process was quite simple. I just opened up the back of the G1, removed the battery, swapped in an already active AT&T SIM card, closed the phone back up, and then restarted it. When the phone had finished booting, it prompted me for an unlock code, which I had received in an email last night.

Nothing complex – just 8 numbers. Each code is different and is linked to the IMEI number for your phone, which you can find by entering *#06# on your phone’s keypad.

5 seconds or so after I entered the code and hit the unlock button, I saw a brief message on the phone saying that it had been unlocked. And that, as they say, was that.

First thing I noticed was an improved signal. AT&T is stronger in my area than T-Mobile. You can see the photos in the gallery below showing the AT&T network name on the G1’s status screen. Note the lack of 3G data, though. The G1 doesn’t support the proper network frequency bands to work on AT&T’s 3G network, though it will work overseas on 2100MHz networks.

The only thing left to do was to see what worked. Unlike when you typically swap a SIM card, I didn’t get a message asking me to re-login to Gmail. I suppose that is because it had no access to data at all. Web browsing and email with WiFi disabled just didn’t work. Somebody is going to have to come up with a way to reconfigure the network APNs before networks other than T-Mobile’s can be properly used.

Update: Well now, aren’t I a moron? Seems there is an APN section in the Wireless Settings, and all one has to do it add an APN for AT&T. In my case, the APN was “isp.cingular”, the user name was “ISP@CINGULARGPRS.COM”, and the password was “CINGULAR1”

Everything still works fine with WiFi on, too, and SMS sending and receiving also worked just fine with the AT&T SIM.