Hello.
I've recently got a Motorola V557 GSM phone. It's quad band and at the store (Cingular) they called it a "World phone".

The other phone I was looking at was the Motorolar ROKR phone (the one that supports i-tunes) It was not discribled as a world phone, and it is infact only a "tri-band" phone.

I'm wondering if both of these phones would be suitable ,for say, a trip to Europe or Argentina? ( the last 2 places I've traveled to)

Secondly, I'm somewhat confused with the whole "Sim" card thing. I've read and searched a few threads where people talk about "putting in a new sim card when going abroad" and "having my phone unlocked"

Does this have to be done because these people don't have a World phone ? Or is there some other reason for this?

Any replys would be most appreciated ^

Thanks, Tattikat2