I took a look at the FCC frequency database and it has four callsigns for them. One is input to the Meds channel, which all FD/EMS have or should have.
The other three show there are a couple of possibilities. Try these out:
154.355 - should be a Base/Mobile frequency
153.89 - should be a Base/Mobile frequency
453.625 - should be a Repeater frequency
I'll update the callsigns for the frequencies in the database.
You could also try those and the other known frequencies without pre-programming the PL's to see if they may have changed them up, if you are not hearing anything.
Of course, if any of the above is true, please submit an update to the database.
Thanks,