what service do you use?
When i went to canada a while back my ATT phone was able to connect thru
a company in canada..Robinson or Roberts?
some phones have chips that allow international usage.
You want to find a GSM phone or provider.
with a SIM card which matches your phone. Here is AT&T site:
http://www.wireless.att.com/learn/international/index.jsp?WT.srch=1
and a CNET review:
http://reviews.cnet.com/cell-phones/at-38-t-formerly/4505-6454_7-32137726.html
I do not know about this business, but here is some info:
http://www.cellularabroad.com/

good luck and let us know what you find out!