If the friend you are trying to text in Mexico uses Telcel as their celular provider, unfortunately texting them won't work :(

Telcel is currently blocking text messages from Textfree.  You should be able to get texts and calls FROM Telcel; you just won't be able to send TO Telcel numbers.

If we could fix it, we TOTALLY would! It's up to Telcel to decide whether or not to unblock us. We've tried reaching out to them but have received no reply :(  It's like that Beatles song...

One of our alert users shared this article with us, it gives some background.