Unfortunately its not broadcasted over any frequencies. They use Verizon RTNA lines with Motorola or CPI handsets in the ER. The dispatcher simply talks and is heard through the handset.
EMS crews can also call in via cell phone to a recorded phone line.
Second Alarmers still calls Abington ER on their private UHF repeater, right? I think they're the only ones who still use routine radio comms for ER notification in Montco.