... in response to Can you use a US Simcard....., posted by Hoda on Feb 3, 2005The simcard is everything. I don't think that what you heard is likely true, in fact I have seen websites offerring simcards that are supposed to work in Colombia. But the simcard actually contains the phone number and service parameters, so a US one will not work unless you have some kind of international roaming deal. International roadming agreements (which are in fact network sharing agreements) are on the rise, but you need to be very careful as to what your deal actually is.
You should be able to take a simcrd from a funtioning phone and put it in most any unlocked GSM phone the supports the carrier's band usage. The Treo 600/650 are 4 band (universal).
The upshot of that is that if when you locate a prepaid or limited airtime simcard, you can swap it into your phone depending on where you are and recharge as necessary....you don't use it, there are no charges.
To see where we are headed with GSM check this out:
http://www.tigo.com.hn/
Ciao
PS: perhaps this will help?
http://www.poorbuthappy.com/colombia/node/5755