Having worked in that world for many years my experience is you won't hear much traffic from those folks. Because their response is often a collateral duty to other full time technical jobs cell phones and landlines are often the means by which they get their dispatch info. Often the lead will call the incident commander for a brief before they roll to get an idea of manpower and equipment needs. Once they roll there's often little need for any comms until they arrive. Once on scene most info is communicated face to face. If you are close to a call simplex radio traffic between techs and support personnel at the truck might be interesting but often its just "Okay we're coming out" as a heads up to get ready and decontaminate the techs.