Before Space Marines got Techmarines and Librarians they had Communications Officers that were a bit of both.

☠ Rogue Trader (1987)

B&W artwork
Rogue Trader rulebook art - inside cover of the hard back & page 92 below the haywire munitions rules

Communications Officers are mentioned as specialist staff in the Rogue Trader rulebook. They are armed as standard Marines and equipped with all manner of scanners and a high power communicator with a 320km range.

☠ White Dwarf 97 (1988)

Diagram with 1 senior communications officer, 4 comms, 1 astropath, 4 psykers
Communications staff field force

Communications Officers featured in the Ultra Marines army list. They did not appear in subsequent lists.

Communications Officers are brethren (ie fully initiated marines) who have technical expertise as well as battle experience. A Communication Officer will usually have held the rank of at least lieutenant before re-training in the communication role. Communication Officers are in charge of all aspects of communications as well as the psychic members of the force. A Communication Officer may also be a psyker.

The Communications Officer and his staff are drawn from the Librarium. According to WD97 the Ultra Marines have over a hundred psyker brethren at their command, which is a lot. It is unclear if such officers have dominion over half-Eldar Chief Librarian Astropath Illiyan Nastase from the same army list.

☠ Rules

Communication Officers (86pts + powers)

M WS BS S T W I A Ld Int Cl WP
4 6 6 4 4 2 6 2 9 9 9 9

Equipment: powered armour, power sword, bolt pistol, knife, long-range communicator, suspensor

They have a 50% chance of being psykers at any of the four psychic mastery levels, though typically only the Senior Communications Officer is level 4.

☠ The Miniature

Communications Officer miniature
Games Workshop advert: Communications Officer Orinoco

One of Bryan Ansell's marketing strategies included naming every metal miniature. Miniatures were often named at the whim of whoever was putting the advert together. Orinoco was the name of a Womble. Space Marine beaked helmets were reminiscent of the popular television characters. The miniature was also advertised as Communications Officer Kendall.

Painted miniature
My Blood Angel Excommunication Officer who I ran as a battle brother or techmarine depending on need

Brother Orinoco was part of the 1987 Citadel Miniatures range. Orinoco was of course not armed with a bolt pistol and power sword like in the rules. Games Workshop didn't make such easy concessions to players. He was armed with a bolt gun.