Traffic on Channel 1 (Dispatch) and Channel 2 (Fireground) are patched through. Here's a breakdown of the trunked channels, everything can be heard on these:
1072: Dispatch channel. On scene operations can also be heard on the channel for minor incidents, or when Fireground is occupied.
1073: Fireground channel. On scene operations.
1702: Only used by command as a talk channel, generally only during high call volume or events. The channel is especially favored by Car 1 (Chief), Car 2 (Executive Deputy Chief), and Car 4 (some mystery battalion chief). ECD can sometimes be heard on the channel when coordinating with RFD command.
1703: Training channel. Rarely used, but all training operations should be able to be heard, as long as they're not using PSTF channels.
1704: Currently unused, the only traffic you'll hear is Brighton FD mistakenly switching to the channel trying to contact Dispatch, as has happened several times.
1705: Currently unused.
1706: Currently unused.