They use different bands for their 3G service, that's why they aren't in the same phone. I'm looking forward to when there is a chip that supports both so that we can get a GSM phone that supports any 3G service (or at least the common North American and European ones). Anyone have any idea when/if such a chip is coming out?
[IIRC, Rogers (Canada) and AT&T (USA) use a non-standard frequency for 3G service, but T-Mobile (USA) and WIND Mobile (Canada) use the same 'standard' frequencies that are used in Europe.]
The way it's been worded by others, it sounds like it's just a matter of tuning the radio to another frequency. Is the underlying protocol still the same between these providers since it's all just GSM?
GSM and CDMA are separate from 3G. That's why either of the GSM models of the NexusOne will work on any GSM network and will work with Edge on any network. It's 3G that's different between these networks.
Also of note, is that most of these chips target a specific frequency (or frequencies). They are not software programmable radios. I imagine that the underlying protocol possibly differs between the different 3G bands (otherwise I would expect that someone would have created a chip that supports all of the common bands by now).
[IIRC, Rogers (Canada) and AT&T (USA) use a non-standard frequency for 3G service, but T-Mobile (USA) and WIND Mobile (Canada) use the same 'standard' frequencies that are used in Europe.]