Internet is up.
Regular phone calls within Caye Caulker and some areas of Belize City work (including Fax).
Cell phones work from time to time. Sometimes it is up, sometimes it is down.
I am not sure about the pay phones around the island, as I have not tried them.
If you have to make an international call from Caye Caulker, try a Net 2 Phone system from one of the Internet Cafes on the island.