Although the phone is 3G capable, it only has the 2100Mhz 3G frequency which is used outside of the North America. North American 3G frequencies for AT&T are 850/1900Mhz so that is the reason your phone only displays the G for GPRS (and possibly EDGE as well). There is nothing you or AT&T can do to use 3G since it doesn't have the North American 3G bands.
Another thing is it has the 900/1800/1900Mhz GSM bands of which only the 1900Mhz is used here in the US for AT&T and T-Mobile. Since you are using it with AT&T, you will have limited coverage without the GSM 850Mhz band.
If you feel that you have to correct some of my posts for my capitalization of some of my words, then just bear with it. It's just a discussion forum where some may be limited by time to answer in well-versed and eloquent sentences.
I already got a PHD (Plain High School Diploma) so ignore my style of writing and I'll ignore your ignorance.
Subject: You can read this-trust me!
I cdnuolt blveiee taht I cluod aulaclty uesdnatnrd waht I was rdgnieg. The phaonmneal pweor of the hmuan mnid. Aoccdrnig to a rscheearch at Cmabrigde Uinervtisy, it deosn't mttaer in waht oredr the ltteers in a wrod are, the olny iprmoatnt tihng is taht the frist and lsat ltteer be in the rghit pclae. The rset can be a taotl mses and you can sitll raed it wouthit a porbelm.
Tihs is bcuseae the huamn mnid deos not raed ervey lteter by istlef, but the wrod as a wlohe. Amzanig huh? yaeh and I awlyas thought slpeling was ipmorantt!
When asked if I see the glass half empty or half full, I responded I see just a glass of water.
Now you know how I think.