Using your phone abroad was once a major no-no. These days, the costs may have come down, but you can still get caught with a big bill if you don't do a bit of planning before you go. First off, check your provider's website or call customer services and grill them. Check out roaming charges on your current plan, call costs from the country you're going to and how to ensure you select the right carrier when you get there. The other pain about roaming is you usually have to pay to receive calls and to check your voicemail. You won't be charged for unanswered calls, or you could just chose to divert all your calls to voicemail. This may be an option on the phone or you may have to call customer service to do it.
Vodafone offers one of the best roaming packages out there -- particularly if you're heading to the UK. Prepay or pay monthly customers can just sign up for Vodafone Passport online or by text. In the UK, you pay the same per-minute charge you pay at home with no connection fee and no charge to receive calls. Then beyond the UK, the Passport group of countries includes most of Europe and Australia. Here, the per-minute charge within the country or to call home is the same as you pay at home, plus a 79c connection fee. To receive calls you have also got to pay that 79c charge.