Im going to Mexico in a few days and was always under the assumption texting was free internationally. now I have come to find out that is not true haha. i have a 3g 2.2 jailbroken, and i was just wondering what is the best/cheapest/possible way to send free text messages.

do any of the cydia messages apps do this (bitesms, mysms?)
if i unlock my phone will it be possible in any way?