I've been with T-Mobile for years. I mean, seriously - my SIM card still says "Omnipoint". I buy new phones and the kids in the kiosk look at it like "What the hell is this?"
Anyway, I'm perfectly happy with that service other than the fact that I never get the cool phones. So I was particularly interested when the same week as the iPhone came out, T-Mobile rolled out a fascinating new bit of technology called Hotspot@Home. Basically they've figured out a way to do a seamless switchover from cell to wifi. So when your new cellphone comes into range of a wifi point, it will switch over presumably to a VoIP call - and you stop using your minutes. It's the seamless part that really makes it fascinating, and a quantum leap over something like a Skype. If it works, then your T-Mobile coverage just got a whole lot better. Forget about the free minutes thing for a minute, I never burn all my minutes anyway. I'm more interested in the coverage. For example, my wife's only complaint about T-Mobile is that there's no coverage in one very specific area, her parents' house. She's there often, and her cell phone never works. But hey, guess what? With this Hotspot@Home thing, we could at least in theory just set them up with Wifi (which they don't have now) and she'd have perfect connectivity. That's nice.
Now unfortunately comes the downside. And there's two of them. First, you have to buy a new phone. I suppose that only makes sense, but they only offer 2 phones with this system, $50 each, and both I'm quite sure will force you down the "Psych! You bought a new phone, you just re-upped your contract for 2 years again!" path. What if you like your current phone? I like my USB and Bluetooth and MP3 ringtones.
Second, the service is an extra $10/month. I hate the nickel and dime stuff, the cell phone companies are getting as bad the cable companies. So not only did I have to pay for a new phone and extend my contract, now I'm paying more money per month for the service. Is it worth it? No, of course it's not worth it! How does it save me any money? Basically I'd have to be regularly going over my minutes every month to the tune of $10. And I'm not even close to that.
So do I want to go through all that trouble just so I can reach my wife when she's at her parents' house? Nope.
Still, though, I do like the technology. Maybe after a generation or so it'll be a standard feature in all phones and services.