Oral

From the mouth; therefore, of words: enunciated. Spoken. Uttered. Vocalised. Phonated. Rendered through the audible vibration of twin infoldings of membrane stretched horizontally across the larynx which modulate the expulsion of air from the lungs.

Oral is a lesser adjective than verbal, and all the less useful for it. When your circumstances seem to call for the flannel-cut expression orally or in writing, consider verbal instead.