My wife is going to Belgium & Italy for a week and I want to make sure we have TEXTING ABILITY (don't care much about voice or data) without exhorbitant fees. She has an IPHONE 5S If I set her up for the $30 PASSPORT PLAN that includes unlimited texting I just want to make sure we get no $$$ SURPRIS

Hi guys, i have so many questions about the current feature of AT&T. I'm going overseas next month, and i just wanna know, if i use iMessage on a foreign network, (Swiss Network) i will be using the 800MB Passport plan data? or is it free? Also, i would like to know any recommendation on how to use