ANTILLAS I is a fiber optic submarine communications cable that extends between the Dominican Republic and Puerto Rico. It has been in service since June 1997 and is operated on a common carrier basis.
ANTILLAS I uses digital channels operating at 64 kilobits per second (kbit/s) that allow over 15,000 simultaneous calls without multiplexing. It consists of six working optical fiber pairs with each fiber pair carrying four 155 Mbit/s Basic System Modules (BSMs), with each BSM containing sixty-three Minimum Investment Units (MIUs), for a total capacity, on each fiber pair, of 252 MIUs.[clarification needed]