I have unlimited internet but limited texts. How can I IM ppl on BlackJackII without having to pay SMS charge?

Question

What website(s) can I can visit on BlackJackII that will allow me to IM friends (using something like AIM) for free without having it deduct from the amount of text messages I am allowed to use each month? I can use the web as much as I went but have to keep my normal texts under a certain amount.