A Link is a communications device that allows users to maintain short range communications aboard spaceships, space stations and ground installations via the local communications grid. Links can come in a variety of different sizes, shapes and designs, and can also be programed to handle more than communication between users. Certain technologies and designs also allow Links to be secured to respond only to their assigned user, and be operated via voice commands, touch sensors, or both.
Earth Alliance Hand Link Edit
A standard issue device for Earthforce and Earth Alliance Security personnel. The links are attached to the back of the users' hand via a molecular bonding material individually encoded to each user and can be operated by voice commands or by touch sensors. Capable of storing several terabytes of data, the Links feature biogenetic ID comparison sensors, which prevents them from being used by unauthorized persons. If an unauthorized use is attempted, the Link will broadcast an audio warning requesting it be handed in to Security and transmits a theft and location report to the local security network. The station's central computer is responsible for handling and assigning broadcast frequencies. 
As seen in "Objects in Motion, a link's security devices can be overidden and bypassed.