I’ve been a T-Mobile customer since 2000. Before that I was with VoiceStream, so basically I’ve been on a GSM based phone for almost a decade. A bunch of months ago, I bought a v1 iPhone from Apple and used it on T-Mobile’s network. The only feature I lost was support for the Visual Voicemail – everything else worked with T-Mo’s network.

When the 3G iPhone came out, I bought a subsidized handset from the local Apple store and moved my number from T-Mobile to AT&T. That got me 3G support, unlimited mobile-to-mobile for a different set of a friends – offsets losing T-Mo based friends – a much higher price per month, one less phone number (as I had a dual line on T-Mo,) and slightly less coverage. It also got me a $200 charge from T-Mo when my number moved because I had another couple months on a contract for one of the numbers.

I called T-Mo to address the $200 charge by re-activating a line to complete the contract – what I learned from them was more than worth it’s weight in gold…

By law, AT&T is required to SIM unlock your iPhone if you pay full price for it because it’s a subsidized handset.

Props to the FCC for this one – they actually enacted a law that helps consumers for a change…

Basically, the law states that any phone that is subsidized by a carrier and bought at full price that it must be made available as an unlocked model.

What this means is that if you’re on AT&T right now with an iPhone, you can contact them and demand an unlock code which will allow your iPhone to use any GSM carrier. Obviously if you switch carriers you certainly lose Visual Voicemail and you most probably will lose 3G support (T-Mo is rolling that out now.)

Does this change your contract obligations to AT&T if you signed up for a cheaper price? Nope. If you want to use the iPhone with T-Mobile, yer paying $200 to do so whether it’s for the hardware upfront or because you break your contract early… either way, there’s a charge. But as the rep from T-Mobile pointed out, you’ll recover that during the first year of your contract.

Consider my plan on AT&T: $89.99/month (900 min/Unlimited Nights + Weekends + Mobile-to-Mobile/3G/Data) + $15/month (1500 text messages) = $104.99

This was my plan on T-Mo: $49.99/month (500 min/Unlimited Nights + Weekends + Mobile-to-Mobile/2 lines) + $25/month (2G/Data/HotSpot access) + $10 (1000 text messages) = $84.99

Between the two plans:

– T-Mobile had better reception where I work

– AT&T has better reception in other places that I visit

– One weird thing with AT&T is that I’ve lost calls for no reason (walking across a street with full coverage)

– T-Mo’s 3G rollout is still in motion so speeds and reliability is unknown right now (or if the phone supports it at all!)

– Of the two ppl I talk to most on the phone, one is on AT&T and the other is on T-Mo. Since T-Mo has a FavFive thing, it’s only costing me minutes it would cost me minute either way, so this way both people I call save minutes.

– I could go with a lower AT&T plan for fewer minutes but then I’d lose nights and weekends which is bad.

– AT&T’s plan also doesn’t include HotSpot access which is sorta annoying

Bottom line: there’s an option this time around and the rep at T-Mo says that he’s signing up people all the time. AT&T does not have to be your carrier if you want to pony up an extra $200 $400 for T-Mobile’s service. And seeing as I was dropping my second line from T-Mo either way, I expect that my bottom line would be around $70/month and I’d give up 3G/Visual Voicemail but I’d also gain HotSpot access for any type of device, have ample minutes and TXT messages…

Have I contacted AT&T for the unlock? No, not yet. I’m betting this will be a very, very painful conversation to have with them and that they will run me around a bunch of phone menu systems… not something I’m looking forward to signing up for. But they have to support the scenario as it’s required by law.

Either way… options are good.

Update: Corrected the price from $200 to $400 for the full price… iPhone 3G pricing is: $199/$299 for new customers, $399/$499 for existing customers in their first year, and $599/$699 for non-AT&T customers.