4-2-1. no where does it say it has to be recorded. I believe you can, make sure you give them a release time so you can protect for the departure. However, getting just a roger is an awful practice, not only do you not have it recorded to cover yourself, you don't even know if they got it right. ask if they can depart VFR, hope they say yes, give them their squawk and a frequency, maybe an altitude to maintain and say they will get their clearance in the air. Then once in the air deliver the rest and its recorded and you're all good. Im assuming they are coming off a satellite airport. Is that why they called on the phone?