I plan to leave my iPhone behind when we go on a trip to Peru (worried about theft) and take an old unlocked Nokia. I'd like to buy a SIM card that will work with the local carrier, primarily to make calls to the U.S. to check for voice messages and a few calls but no heavy business. I did a search for SIM cards and found many companies offering international SIMs (lots based in UK). Anyone got experience and recommendations? Buy in U.S. or locally on arrival? TIA