The Technology Is Not Compatable

I have a nxtell phone which operates on an IDEN network. Unforutantly i hate nextell phones and just bought a really sick phone that operates on GSM netowrks (cingular). If i take the sim card out of my nextell phone and put it into my cingular phone i get service but can only make emergency calls. is there anyway to make the two phone compatable. in other words can i take a nextel sim card and put it in a GSM phone and use it? Are the troubles i am having software issues, network issues or phone issues?