Wow. I never knew of WiMax. So is this the system T-Mobile has developed? I recall reading something about a system that uses WiFi or such and UTMS or something, I'm totally out of my league on this one. Any help? Thanks!
No, you're thinking of UMA, which was developed by the industry, it's just T-Mobile is the first to offer it in the US.
WiMAX has nothing whatsoever to do with Wifi. Other than confusing similarities in name, pretty much the only thing they have in common are that you might use either to access the Internet wirelessly. But that's it. It's like you might use DECT or GSM to access the phone network wirelessly - but DECT is unlicensed, has a range of a few yards, requires you provide your own connection to the phone network, and uses its own set of protocols, whereas GSM is licensed, has a range of tens of miles, the connection to the phone network is provided by a third party which also owns the towers, etc.
GSM is to DECT what WiMAX is to Wifi.
Wait, this is an online forum. So we need a car (or rather transportation) analogy:
Trains are to golf carts what WiMAX is to Wifi.
Makes sense?
As far as UMA (the service you're talking about T-Mobile offering) goes: UMA allows GSM signals to go over the Internet, via a local Wifi connection, instead of over the licensed GSM airwaves. This frees up capacity and also means a user can fix coverage holes themselves.
And UMTS is GSM version 3, and has nothing to do with UMA. AT&T offers UMTS already (that's what is often called 3G - UMTS is one of many 3G standards - or HSDPA - a technology provided in some UMTS implementations improving performance.)
So:
Wifi - a short range data networking standard, mostly used by people to access the Internet via their own network (or provide internet access to people on the owner's property.)
GSM, UMTS - 2G and 3G voice and data cellular standards. GSM is usually augmented by GPRS or EDGE to provide Internet access. UMTS is built with Internet access from the ground up.
WiMAX - an Internet-oriented cellular networking standard.
UMA - a way to use GSM (and UMTS) over Wifi and the Internet instead of the normal licensed spectrum. (Actually, the original standard supports Bluetooth in addition to Wifi, but that never took off.)
Other standards include EVDO (competes with UMTS but rare outside of the US, less open and capable than GSM based standards), and "UMTS rev. 8", sometimes called Long Term Evolution, which is the 4G version of GSM and a direct competitor to WiMAX.