If you're among the many who are lucky enough to have an iPhone and to be able to travel overseas on vacation this year (or maybe you're unlucky enough to have to travel overseas every week on business), you'll soon run into the pain and expense of trying to use your phone while you're away from home. And while AT&T's charges for international roaming are stunning (I get charged for people who leave me voicemail even when I don't answer the phone?), as our friends at TUAW point out, it's no better if you're visiting the States, either.

I was recently in the UK on vacation, and I wanted to share couple tips you might not know about using your iPhone - without using the phone - after the jump.

If you don't want to get stuck with huge bills, one of the first things to do, of course, is to turn off Data Roaming. This is off by default in newer US phones, or you can do it in the Settings app (under General / Network). But you'll still get charged for making phone calls and, as I mentioned above, for receiving them - even if you don't actually pick up the phone. If your Aunt Hilda calls and leaves you a 5 minute voicemail, AT&T will charge for 5 minutes of international roaming (in some cases, they may also charge you the round trip - 10 minutes' worth of calls). Or if your friend decides to send you a bunch of texts at 3 in the morning because he doesn't know what time zone you're in, you'll pay for those too. (This is often not true for non-US carriers; check your carriers' international roaming terms before you leave home). What's AT&T's recommended solution if you want to avoid paying for anything unexpected? "Leave your phone turned off."

Now that might be fine if the iPhone were just a phone, but when it's also your language translator, your guidebook, and your camera - that's not so great of a solution. Enter Airplane Mode. Airplane Mode turns off the transmitting devices in your iPhone, including the 3G radio, WiFi, and Bluetooth, letting you use your iPhone without having to be surprised by expensive texts or phone calls voicemails.

But Edwin, I hear you say, the iPhone is a great data device. Why can't I at least use WiFi and still avoid Aunt Hilda? The answer: you can. Once you've turned Airplane Mode on, you can still go back and manually turn on WiFi. This will basically turn your iPhone into an iPod touch. So at the very least, you can sit in a Starbucks anywhere in the world and look up how to say "Vente Chai Latte" in the local language without worrying about getting dinged for using your phone.

Once you have data over WiFi, you can use email, VoIP apps, or, my personal favorite, AIM, to keep in touch with friends and family back home. If home is in the US (or you're trying to reach someone here), you can also use AIM to send SMS text messages for free. Just enter the 10 digit number preceded by +1 as the buddy name. Your friends will even be able to respond, all without your paying a dime (above and beyond your WiFi connection). If you don't have an iPhone but have an iPod touch, you can still use AIM to send free text messages to the US from wherever you are.

By employing judicious use of Airplane Mode, and using apps like AIM over WiFi to keep in touch, you can still use your phone and stay connected. What's even better, you can save some money that you can use to buy some more apps or tunes. And you know those will come in handy for those long waits at the airport.

We hope all of our readers travel safe and have fun this summer.