Well today I finally got through - sort of. First it rings twice, and I get a recording saying something to the effect that "This service is not provided on the global network." Whatever that means. Then I get a couple more strange sounding rings, then a pause, then it finally rings my friend's cell phone in Santo Domingo. Weird stuff. This is calling direct from my job in New York City, which uses AT&T as a carrier, to a cell phone in Santo Domingo, with Tricom as service provider.
I assume they're working out whatever problems they've been having, as yesterday all I got was incessant busy signals.