Hey, Bob. Jeff here, a T-Mobile customer who rocks out your hotspot network regularly enough that I’m strongly inclined to stick with your service. You’ve also generated some longterm loyalty from me by being the first provider on the block to offer a cheap, unlimited data plan.

Thing is, there’s this new phone coming out, and I hear that your industry is nervous about mass migrations to AT&T. Sprint and Verizon are about to discover that CDMA stands for See De Masses Abscond. But you’ve got GSM, and I’m thinking it’s about time you made that mean Got Some Mojo.

Here’s the deal:

1) With the unlimited data and Starbucks hotspots, you’ve got yourselves a nice geek community ponying up to you monthly—at least, everyone who didn’t get tired of waiting for your 3G service. But the people who switched to EVDO can’t use an iPhone, can they? So perhaps they’ll be coming back to a GSM carrier.

2) You can’t sell the iPhone, so a lot of your customers are going to be looking at AT&T…

3) but your network works just fine with the iPhone, provided the phone is unlocked.

4) In case you haven’t noticed, it’s illegal for Apple or AT&T to prohibit unlocking the iPhone. There’s a specific exemption in DMCA for this.

5) So the only real barrier for the unwashed masses using their iPhone with T-Mobile is a service to unlock their phones…

6) and the $175 service fee that AT&T will charge for buying an iPhone and immediately canceling.

7) $175 is what, 45 days’ revenue from the sort of heavy cellular user who would consider buying an iPhone in the first place?

8) Do you see where I’m going with this yet?

The iPhone ships at 6 PM Friday. So I’m thinking that on noon Thursday, you announce that any T-Mobile subscriber, old or new, can walk into any T-Mobile store to have their iPhone immediately unlocked, and receive a $175 credit on their account.

And if you’re not doing this—why the hell not?