For most people with Eurasian versions of smartphones, you only choice for full 3G is
using AT&T because of the frequency issue. Only AT&T uses the same frequencies at
1800MHz and 2100MHz spectra for WCDMA. The reason why many can't attain 3G speed on
T-mobile USA is that they use 1700MHz and 1900MHz frequencies for WCDMA which is not
supported by phones outside US. Hence your iPhone would only see 2100MHz for GSM and
attain EDGE speed at maximum.
Luckily I got a T-Mobile USA version of Nexus S, so I can be different and use USD3 a day
unlimited phone + data at HSPA+ speeds for the first 200MB.
In response to the following email:
http://lists.wikimedia.org/pipermail/wikimania-l/attachments/20120617/056a4…
Best regards,
Alan Lai
Sent on the road