AT&T customers in Springfield should have noticed an increase in the speed of their mobile data connections last week, as the company announced an upgrade to its capabilities in the capital city. Cell phones operate on electromagnetic frequencies between 800 megahertz and 2,700 megahertz and, while different cell phones and different companies use various frequencies within that range, AT&T’s announcement basically means they’ve started utilizing more of those frequencies in Springfield, as well as in Athens and Petersburg. The result is that phones using AT&T mobile data in this neck of the woods should be able to send more data at once with faster speeds. While Athens and Petersburg are still on the third-generation “3G” connection, the upgrade improves the fourth generation “4G” data connection already available in Springfield. “It’s adding capacity to what’s already there – basically adding more notches to the belt,” says Susan Diaz de Leon, a spokeswoman for AT&T. The move may also improve the quality of voice connections, but with the explosion of text messaging and email-capable phones, using your cell phone to make actual calls is almost an afterthought.