NEW YORK ( MainStreet) — Most of us who travel overseas have had this creepy moment when, a month after the trip, our cell phone bill balloons by an extra $100 - sometimes much more - and that is not for voice calls because we made none. It is for data services that nowadays have become part of our daily fabric of life.

Worse: many times we are not even aware the data meter is running, because a lot of that data dribbles in on its own: Apps updates, Facebook and Twitter posts by friends, you name it.

Three facts about foreign travel: (1) It is easy to turn off that barrage of unwanted, expensive data (turn off data roaming under Settings); (2) Voice is not the problem overseas, it's easy to get cheaply (think Skype and Google Voice); (3) The problem is accessing the cellular data we want and need.

The good news: there are surprisingly low cost solutions for getting cellular data overseas.

What's new is that, in a very few years, many of us have become addicted to cellular data in motion (can you find your way to the nearest Starbucks without Google Maps?). It gives us directions on the go, it finds what we are hunting (do a quick Google search for "galleries Berlin Mitte"), it delivers weather and flight alerts and of course there may also be a stream of SMS texts.

The problem is the cost. Without a global data plan, one megabyte of data in Italy will run you $19.97 with AT&T. Ouch indeed, but there is no reason to pay that tariff. Simply sign up with AT&T's global data plan and $30 buys 120 MB in 150 countries.

Sound good? It isn't awful and a plus is that just about all of AT&T's phones are based on the GSM cellphone protocol and thus global ready, which cannot be said about Verizon's CDMA-based phones, many of which are castigated by users who say they were let down overseas. Europe, for the record, is monolithic GSM and although there are some CDMA pockets outside the U.S. (South Korea, Japan, parts of South America) there are subtle differences that effectively make it impossible to use CDMA phones from the U.S. there.

But then there is a Verizon secret that turns its global ready phones - it claims there are some 25 including the iPhone 5S and HTC One - into low-cost data powerhouses abroad. That is because when Verizon made a recent deal to buy cellular spectrum - air space for transmission - it promised the Federal Communications Commission it would leave the SIM slot in 4G LTE phones unlocked. That means any owner can waltz into, say, a Telecom Italia (aka TIM) store in Rome, plunk down around $30 and walk out with a local SIM that includes prepaid cellular data access at six Euros for 500 megabytes.