You have done a good work, however Mobicity is not a telecommunications provider but a services that sells cell-phones?Oh, that's cool. That's funny because I do rooted development for the Incredible S on XDA.
I'm guessing you use Virgin mobile or Yes! Optus for your carrier? Not Mobicity or Telestra, right?
If this is right, your 3G carrier is actually T-Mobile. I think it works like this:
Mobicity: 2G: all, 3G: 850mhz
Optus: 2G: all, 3G: 900 & 2100mhz
Virgin: Same as Optus.
AT&T: 2G: all, 3G: 850 & 1900 mhz
T-mobile: 2G: all, 3G: 1700 & 2100mhz
So in the USA:
2G/GSM both AT&T and T-mobile are fine
3G frequency you will need to use T-mobile, AT&T won't support that model.