Beware of "slammers" on your prepaid SIM while traveling!
Traveling in Italy with our phones using TIM pre-paid SIMs, we encountered a problem with my wife's balance draining faster than it should have.
Checking in with a TIM store, we found that her account had been "slammed" by a service called Jamba, which provides ringtones, videos, music and games aimed at pre-teens and tweeners...and it had been deducting €5 a week, more than the cost of our phone service!
Lesson: when buying the SIM, ask the clerk (if you're in a phone store) to put your number on a blocked list for added services that do not come from the carrier. If you buy the SIM elsewhere, call the customer service line with the request. And DON'T ignore text messages you don't understand or assume they are from the carrier; use Google translate or other means to know what they are.
The positive side of today's discoveries: The current version of the Google Translate App for phones has a menu option for SMS translation. Select, and it opens your message list, and translates any one you select. Had we known, we probably would have spotted the Jamba slam right away.
Incidentally, the app also now lets you use the phone camera to grab blocks of text for translation. Great for menus!