Translink frequency

The translink frequency (or translink signature) was a frequency unique to the interplexing beacon of each Borg drone.

In 2375, The Doctor determined Seven of Nine's translink signature aboard the Delta Flyer so that her shipmates could send her a message during a mission to rescue her from the Borg Unicomplex. 

''In an alternate timeline in 2390, Chakotay and Harry Kim requested that The Doctor extract the interplexing beacon from Seven of Nine's corpse in order to determine her translink frequency, which would allow them to send a message to her in the year 2375. The Doctor found that Seven's translink frequency was 108.44236000.''