Russell Shaw has a pretty damining post today on what sounds like serious VoIP-blocking being done by Belize Telecommunications Limited, the local telco in Belize. The good news is that it seems that enough people have made enough noise that the Belize PUC is getting involved, and Russell points out that some very influential people there are not at all happy with the situation:
Well, on Wednesday, the Belize PUC will hold a hearing on the matter. Expect to hear from some very influential people, such as Andrew Godoy, director of the Belize Tourism Industry Association. “The Board is appalled by the actions of BTL,” Godoy tells the San Pedro, Belize Sun. “We have heard from many of our constituents and this is negatively impacting their business.”


They are indeed blockin some forms of VoIP. My personal experience was with Vonage "jamming". They are using an application layer FW to inject phony SIP messages indicating to my Vonage ATA that the call is "busy" or "cancelled".
Full technical report is here:
http://www.vonage-forum.com/ftopic12433.html
Belize Free Internet Consortium
http://bfic.wordpress.com