IPhone 3G to iPhone 4, upgrade?

I have an iPhone 3GS right now, I got an iPhone 4 from my boyfriend, if I went to AT&T to get a SIM card for the iPhone 4, would that count as an upgrade? I'm trying to get out of my upgrade.

The upgrade is only if you buy the phone from them so no.

No it will not count as an upgrade. If you are a current att customer with a contract go to an att corporate store and they will give you the SIM card for FREE.