Why Unlocked Phones Don't Matter in the US

This is the second post in a row with a title that start with "why". I wonder if it's due to Google Nexus One "why" moment.

Anyway, as the title says unlocked phones don't matter in the US. Here's the reasoning that made me believe so.

There are four major cellular network carriers in the states: Verizon, AT&T, Sprint, and T-Mobile. Verizon and Spring use CDMA technology that seem to be used primarily in USA while AT&T and T-Mobile employ a more recent GSM tech widely deployed worldwide.

CDMA and GSM are not compatible at all which reduces the number of major networks an unlocked phone can be used on to just two. That means you can potentially use your unlocked phone on either Verizon or Sprint or on either AT&T and T-Mo. They keyword here is "potentially".

Further "research" reveals that portability between the major US CDMA carriers Verizon and Sprint is not universally guaranteed and an arbitrary phone will unlikely to work on the other network even if unlocked.

While GSM was designed for portability, there are still minutiae on the technical side that can prevent full compatibility on the data side, which is essential for smartphones such as Nexus One. Specifically, different GSM carriers use different radio frequency bands for GSM 3G data transfer. It happens to be the case that AT&T and T-Mo are just such carriers meaning an unlocked Nexus One will only work on T-Mo's 3G network but not on AT&T's.

Now I'll ask you a question. What is the point of buying a $530 unlocked phone if the only major network you can use it on is T-Mobile?