Mine was bought directly from Google with no carrier branding or software. They first version that came out was only for T-Mobile, then they released a version for AT&T. Different frequencies for 3G. Could just be a software change I suppose, but as far as I know they can't be switched (certainly not by the end user in settings) by a software update. If Google could have released one phone that allowed a user to switch back and forth I would think that they would have. The US is messed up when it comes to comparability across our carriers, even the two GSM carries use different frequencies.
Originally Posted by phlojo
Isn't that carrier-specific though? Why would they invest in 2 different hardware versions of the same phone, and why would we not hear about it after all these years? I think that in your case one has a software setting or some patch applied to limit the high speed mobile internet access to a specific carrier.