I have 2 cell phones, my Treo on Cingular and a Telcel account in Mexico (I work in Mexico). I am sick of carrying 2 cell phones and i wish my Treo would handle both lines. I found on eBay a "dual sim card". I don't know if it would work with a Treo or if it even does what I want to accomplish. Take a look and please share your comments. Thank you.