The Castor has been badly damaged by previous attacks. One whole wall of the flight deck was vaporised by an anti-matter drone, so the flight deck is open to space. So, when taking their 4 hour shifts the pilots, navigators and engineers working on the deck have to be in space suits the whole time. This does limit how everyone can communicate.
Radio Channels
Just as the defence wings communicate on radio channels in space, there are a number of radio channels (e.g. Castor Fighter Bays, Engineering Comms, Bridge Link…) on the Castor. While in the flight deck, you can join any of these channels, and talk with audio only with any number of others.
These are Discord audio-only channels, which any number of players can join
Of course, if you want a private conversation, these are not ideal. Anyone, including the Bridge crew, can drop onto these channels at any moment.
Suit Interconnects
When you want to talk to someone else privately, you only really have one option – look into each others helmets, and connect your suit radios together directly with an interconnect cable.
Then you can see each other, and no-one else can listen in.
These are Discord video channels, which will only accept two players. If you want to connect with another character privately, you can both join any of the interconnect channels.