While most talk of a non-AT&T iPhone has been directed at the #1 carrier, Verizon, there’s a growing thought that T-Mobile may be the first new service provider to carry the Apple phone.

Kaufman Bros analyst Shaw Wu suggests that an iPhone that doesn’t run on AT&T is “becoming closer to reality than ever [and] could happen as early as this fall.”
Most people are talking about a Verizon iPhone, which is likely to come out at some point. However, that will require a technological overhaul since Verizon and AT&T run on different mobile standards.

T-Mobile, meanwhile, is the other main carrier in the US that runs on a GSM network, the same kind as AT&T. Based on that, Wu thinks Apple will target T-Mobile first, if for no other reason than the quick turnaround.

“Interestingly, both the new iPhone 4 and iPhone 3GS support 3G at the 2100 MHz frequency and, from our understanding, the technical hurdle to support T-Mobile is minor compared to supporting CDMA technology at VZ and Sprint,” he said.

Moreover, though, T-Mobile needs the iPhone more than Verizon does. Verizon easily takes the title for most customers in the US, and it holds the exclusive rights to the solidly second-place phone in terms of sales: the Droid.

“Also, we are picking up that T-Mobile views the iPhone as key in winning back lost customers and as such could be more likely to agree to Apple’s terms,” added Wu.