Are you in a part of 309 that has Cingular Wireless service? If so, did you sign up for service at a dealer in the 217 area code? The dealer may have signed you up for 217 instead of 309. I don't know how assigning phone numbers for a specific area code work when going through a dealer. Maybe it's determined by where you signed up for service at.
I ordered a Cingular phone. I just received an email with a phone number and the area code for the number is 217. Where I live the area code is 309. Have you ever heard of a cellular provider giving you a different area code then where you live??