Dating on mobile in usa
This is partly true for Alaska, Puerto Rico and the US Virgin Islands too, but additional operators offer mobile services there shown in own Puerto Rico (incl. Other US overseas territories where different providers run are featured in separate articles like these of Guam or Samoa.
There, the same operators are on the air forming one common network without roaming fees.
This was (almost) the only operator in the world on this frequency, so hardly any non-T-Mobile US phone could cope with it.
AWS is sometimes referred as “1700/2100” MHz suggesting a 2100 MHz phone would work.
To really work out the differences you have to compare the frequencies of your device with the frequencies offered by AT&T and T-Mobile as there are a lot of incompatibilities with devices from out of the US.
For major phone models it's shown here how to check it.