Sandy I finally got an answer for you. It's from Steve Cywin who you know from Wreckmania and who was on my last Bonaire trip.
Basically, the rooms have standard RJ-11 (US style) phone jacks. If your ISP provider has a local phone number in Bonaire, then all you need to do is write down the number before you go and logon once you get there. You will get charged for a local phone call like you would in any hotel, but that's it.
If your ISP does not have a local number, then you might want to sign up with another ISP that does have one before going. I use attglobal.net and they have a local number in Bonaire.
Steve