They have two radios, why? Some of that is probably because the two crew members aren't necessarily together - if the paramedic is in the back they don't have direct access to the front, where the driver/EMT is located, so the paramedic needs an HT to talk from the back if need be, to the hospital, and of course they need to take it into the patient's home, also. When driving to the hospital, whoever is driving needs to be able to communicate with dispatch, also. If they have two mobile radios,