Your going to want to keep your service technicians off the phone while operating a commercial sign truck. Strict new guidelines for the use of cell phones are taking affect and will impact your sign company. While the penaties are very stiff, it's in the best interest of the public to keep drivers focused on the road.
The United States Department of Transportation issued a new safety regulation that prohibits interstate commercial truck drivers from using hand-held cell phones while operating a commercial motor vehicle (CMV). The ban is effective January 3, 2012 and will affect sign industry truck drivers who travel across state lines. Drivers who violate these restrictions face federal civil penalties of up to $2,750 for each offense and companies that allow their drivers to use hand-held cell phones while driving face a maximum penalty of $11,000. Enforcement of this provision could be triggered simply by your driver telling an officer that the company requires the driver to use the cell phone.
You are allowed to use a hands free device. This law is basically already in affect for California.