The only thing i can think of in terms of people calling on the ground is due to a noise abatement procedure that probably wasn't followed...ODP's are flown in lieu of other clearance and departing VFR, or you can reference your company's 10-10 pages which more than likely spell out what to do..ODP, in my opinion, is the last thing flown and referenced only when the tower is closed and you need some form of guidance in the transition from vfr-ifr....