Unlocked cellular phone

I think that to make cell phone calls in Europe you'll need an unlocked dual band GSM phone and a SIM card.

You may use a tri-band 850-1800-1900 unlocked cell phone in Europe, but you'll be giving up coverage in the 900 band, which is the most common band for international cell phone communications.

Many companies in the US sell locked cell phones which provide only one SIM card option for use with each phone linked to one particular carrier. This is called a "locked" phone. This is not what you want. Unlocked cell phones allow the use of any SIM card, as long as the frequency capabilities are correct. Unlocked GSM phones are what you need.

You're best off purchasing your cell phone and SIM card in the US from a dealer who specializes in selling and renting cell phones for use abroad (This is especially true for the SIM card itself, since most countries in Europe sell SIM cards only to residents). Another benefit of getting the card early is that the number of your phone is embedded in the card, so you'll be able to give that number out to family and friends. You'll activate the SIM when you get to your destination. You can easily add calling time to the original SIM so you don't have to change numbers each time you run out of call time.

You can also rent a GSM cell phone. Some come with auto rentals and leases. But the rent on the phone along with the high usage rate often makes purchase a better deal--you'll probably pay for the phone after the first trip if you make many calls.