Final answer:
If unable to contact the dispatcher from a MVC with a portable radio, you should try different communication methods or positions possibly using a vehicle's mobile radio or sending someone to where they can communicate.
Step-by-step explanation:
When at the scene of a MVC, and you attempt to contact the dispatcher with your portable radio but are unsuccessful, you should move to a different location to try and improve communication, use a mobile radio in the emergency vehicle if available or send someone to a nearby location where they can communicate to the dispatcher.
It's critical to maintain communication for coordination with other emergency responders and to ensure additional resources are deployed if necessary. In cases where radios are not functioning using other forms of communication such as cell phones or even road flares or emergency lights to signal for help may be necessary.