desk phone during missions

What are the "desk phones" used for in some missions.  Do they require a certain skill load to use.  When "used" nothing seeems to happen.

Thankyou for the above replies.  They are appreciated.  I have more to share though.

The other day I encountered another one in a mission.  It was a normal mission.  Not a critical or archived mission.  They seem to appear at random.  They only have a "use" option with them.  Are they only meant to be as interactive as a chair or light switch?  Were they once used for other things and never taken out of the game?  When used, there seems to be no animation with them.  The in-game chat only says something like "desk phone used."  I have never had to use them as a mission objective.

I don't know what their use is, but since they are there I am wondering their purpose.