Joe, yes the dispatch tones are for VEMS and go over the Valley MED 10 tower.
Though the "matrix" switching computer is old, it is a great set up. I can use any MED patch channel for an ambulance to communicate to any hospital in our region. So say a crew in Meriden needs to talk to a doctor at Yale for a trauma alert from the scene. I can hook the Yale hospital radio to the MED 3 tower and they can talk from the scene.
This option comes standard on the Centracom II you can patch any module to any module.
If you have a module for a tower in Alaska you can patch it to Yale
We had a phone module so any phone could be patched to any module and a scanner module we could program the scanner to whatever then patch it to a channel, the guys in the field loved it.
We also had a TV module for the TV audio to come over a speaker, that was always fun to patch to a tac channel LOL