[GadgetKen]

That would make sense with the CelTrek card working because it didn't need the Pacific cable.
After some thought, my solution for another card may actually be a Digicel card. Travel to the Caribbean for pleasure, and their sim cards are good for inexpensive roaming across their the entire Caribbean network (can also roam on Cingular in the US for about a dollar a minute) plus I could refill over the web to keep the card alive between trips. Would also give me data if I signed up for it. Cable and Wireless bMobile service is another possibility but I've generally had better luck with Digicel for voice quality and call completion.
For travel to Canada (business) I have Fido, and for an aviation museum trip to the UK in the fall I can use the United Mobile card.
Still might consider CelTrek in the future if they offer data and United Mobile doesn't come up with an offer to compete.