Multiple radio sets

Dispatch-reliant services, such as tow cars or ambulances, may have several radios in each vehicle. For example, tow cars may have one radio for towing company communications and a second for emergency road service communications. Ambulances may have a similar arrangement with one radio for government emergency medical services dispatch and one for company dispatch.

Multiple controls, microphones

A mobile radio in a US ambulance often has two sets of controls: one in the patient area and another near the driver.

US ambulances often have radios with dual controls and dual microphones allowing the radio to be used from the patient care area in the rear or from the vehicle's cab.^[2]

Data radio

Both tow cars and ambulances may have an additional radio which transmits and receives to support a mobile data terminal. A data terminal radio allows data communications to take place over the separate radio. In the same way that a facsimile machine has a separate phone line, this means data and voice communication can take place simultaneously over a separate radio. Early Federal Express (FedEx) radio systems used a single radio for data and voice. The radio had a request-to-speak button which, when acknowledged, allowed voice communication to the dispatch center.
Each radio works over a single band of frequencies. If a tow car company had a frequency on the same band as its auto club, a single radio with scanning might be employed for both systems. Since a mobile radio typically works on a single frequency band, multiple radios may be required in cases where communications take place over systems on more than one frequency band.^[3]