[Surgicalcric]

Not every firefighter has a radio, but all of the fire officers do and so do the engineers as well as both EMS crew members.

It is the responsibility of the first arriving engine company, rescue company, or Bus to initiate Incident Command and thusby ensure proper management of the incident: personnel, assets, subordinate commands. As other officers higher in the CoC arrive the responsibility of Command may continue with the initial IC or it may be turned over to a ranking officer, which is the general rule.

Once the fire officer/firefighter/paramedic initiates command a dispatcher is then dedicated to that incident and Command will be assigned a tactical subgroup (channel) for all radio traffic from then on to be carried on. This keep from congesting the dispatch and med channels with the chatter of command. The IC will be talking on 3 or 4 different subgroups depending on the incident and what agencies are involved.

The purpose of every person having the ability to talk is you never know who will be the IC or area command and for how long that person may be in a command position before relieved. Many will never even use those subgroups, but they are there if the need were to arise.

Edited to add:
The old days where an individual could just key up a radio and make stupid comments or play the stereo in anonymity is long gone. Each time I key my WT or mobile everyone else on that given subgroup can see, on their LCD display, whose radio it is thats been squelched. All the radios have identifiers individual to that user.