While they have at least enough range to reach a ship in orbit, communicator transmissions do not penetrate dense materials well. If a starship's internal communication system fails, individual communicators are not sufficient to provide ship-wide communication through the ship's bulkheads. A variety of other phenomena, including electromagnetic radiation and various types of particle radiation, can interfere with communicator transmissions.
In the 23rd century, a communicator was a hand-held device normally carried in a case attached to the user's belt. In the 24th century, communicators have been further miniaturized and built into the insignia worn on Starfleet uniforms. 24th-century communicators also serve as transponders, allowing a friendly starship to locate a functioning communicator at will. A 24th century communicator can also serve as a security token, allowing restricted commands -- such as control of security force fields -- to be issued by voice through the communicator.
Worf once modified a communicator to generate a personal force field during a holodeck simulation gone awry. As nothing similar has been seen in any other situation, it's possible that he just used it to hack into the holodeck's own force field generators to make them create his personal shield.
- TNG "Disaster"
- TNG "The Hunted"
- TNG "A Fist Full of Datas"