A comms console is used to trade with passing interstellar trader vessels or for communicating with other factions, and is locked behind the microelectronics basics research. You will not receive any notifications about passing trade ships until it is built or if the electric power is cut off due to solar flare. It cannot be reinstalled.
A comms console not under a roof will cause shorts during rain or snow. Take care with placement outdoors, despite them being depicted with satellite dishes on top.
Select a colonist and right-click the comms console.
Ordering a colonist to use the console will bring up a menu showing the available factions, or trade ships.
When interacting with an allied faction, you can request trade caravans from them. Doing so will cost 15 goodwill, and brings up a menu asking which type of trade caravan is desired. After a caravan has been requested, you can make another petition after 4 days.
In addition, you can request immediate military aid from allied factions. This costs 25 goodwill. Only outlanders will send reinforcements in the form of drop pods, while tribes will politely decline.