Recently, Clark heard from a listener who took an iPhone to Europe and got hit with more than $5,000 in fees for overseas use. Now The Los Angeles Times reports that a woman went to Canada, made 6 calls totaling 15 minutes and was billed some $2,400 by T-Mobile. That's about $158/minute!

Meanwhile, AT&T has a new add-on plan for iPhone users that should help deal with the massive overseas charges. For $120-$200/month, you can buy coverage that allows you to use your iPhone outside of the United States.

Here's a general rule of thumb: Before you go abroad, get in writing the terms and conditions that will apply to phone use overseas.

But realize that there is a much better alternative. Get a pre-paid SIM chip to use in an unlocked world phone. Clark typically uses GoSIM.com to purchase chips, but he also recommends Telestial.com.

Whatever you do, don't trust a stateside cell carrier with your wallet while overseas!