Do I have to pay for cellphone instant messaging?

I am getting a prepaid cellphone though alltel. I am getting the LG scoop. I know you have to pay 10 cents for each text you send, but does that count also as IM. The main reason I need the qwerty keyboard is for IM and e-mail. If I do I might as well just use the computer only for IM. I will still get the phone though.