On the open channels
Choir ships broadcast a looping signal on open channels. Their crews live in the Void, worship the Span gates and strip ships on the routes they guard.
They guard relic sites as well as routes. For an explorer, an old structure can be a discovery and a guarded place at the same time.
The Cinder front
In Cinder, the Choir fights the Wardens. The conflict gives pilots a place to choose a side and make their own record.
What the Choir hears in the network remains part of the mystery surrounding the gates.