It is in the title, but in case no one caught it. It is on Cingular service. So the trade would have to be for a cingular phone with the sim chip. All you do if you want to trade is contact me, we can meet up, swap chips, and presto. Done. It will not effect your contract, service, or anything. If you want the data service though, with email and such; you would have to contact cingular and have it added to your plan.