On Mon, 14 Jul 2008 21:05:13 +0000, Larry wrote:

Callsigns must always be used in international waters and foreign ports of
call.

Oh yes, especially in the Bahamas where everyone carries a VHF hand
held on shore to call taxis, make restaurant reservations, etc. Never
have heard a call sign there. The local convention is that channel 6
is for taxi service.