I'm guessing it's probably EA28 (with the emergency dialing fix). If the Build Number on About Phone says DL09 or DI01, you aren't on the latest 2.1 update. To update go to About Phone-System Updates-Check New. Make sure Wifi is off.
you all act like samsung is so terrible. htc released the eris ~november 2009, it didn't have 2.1 until may 14th the following year. the fascinate has gotten numerous updates since it was released, and it's still under the 6 month it took htc to release a new os. so, stop complaining.
and google released 2.1 in january 2010, 4 months time to get it to the phone on the eris, and it only had a few models to it. the galaxy s is a huge line of phones. this phone's only been out for 4 months and we already have froyo.