Is it easy to buy a SIM on arrival? I'm going there on holiday in a couple of weeks and my first couple of days are going to be in the rain forest. If I can't grab it at the airport, it will be a while before I can get it.

With respect to Panama (Gary's question), I was there last year and had great 3g. I made calls over 3g all around the country. You can buy the SIM on arrival. There is a vending machine right after you clear customs. It looks like an ATM. There was also a place right next to inbound duty free that sold them.

Perhaps a SIM cutter would be something to add to your gear?
I am sure other crew members would love to use it also?

If you are an OFW, perhaps you could leave a message in the suitable forum about Philipino SIMs available that might be of interest to people in other countries? I have SMART Buddy I use as an international SMS card.