Apple iPhone in the US is locked to AT&T and this has really strained AT&T’s network heavily. With no MMS and Tethering till date, iPhone owners with ATT aren’t the happiest of the lot. Apple has sold 30 million iPhones and is surely looking to tap other consumer bases. Spring, Verizon, TMobile all would be more than happy to get the iPhone onboard. With Apple’s exclusivity agreement with AT&T ending in April 2010, there are speculations that Apple might go beyond ATT here.

ATT has recently invested $31bln in network up-gradation. This makes their reliance on the iPhone really heavy. It would be interesting to see where this ends!