Do you have two way radios in your trucks? the reason I ask is because use hand held Kenwood two way radios connected to peltor headsets which work pretty well, the crane cabs have truck radios in them so the operator can talk to the people on the jobsite or truck a couple miles away.
The best part we have our own frequency so we don't have to listen to c.b.s baby monitors or little kids' toy walkie talkies.