Thanks for the your replies. My main concern was whether I would still get charged with just using my 3G connection because a lot of posts I have read in different sites people say that it's only free internationally with a wifi connection and I don't have wifi at the moment.. I do however have unlimited data usage and as long as we're both using iPhones, iOS5 or higher and have both our iMessage turned on, then it's still FREE with ONLY my 3G internet?
Sorry, don't mean to sound like I don't get what you're saying, I just share a plan with other people and although we all have unlimited everything, I don't want any issues with them about it. Yes I pay my own part of my bill but I am not the main account holder so there's no way for me to check if I was getting additional charges or not...
----------
Also, I have turned my "send as SMS when iMessage is unavailable" off.. And when I say I wanna make sure I'm not getting an additional charges, I mean DATA charges. But if I have unlimited data then I'm assuming that shouldn't be a problem..