Undercover police officers made purchases of narcotics from D on two occasions. Both transactions were observed by another police officer. Officer Zinselmeier testified that on August 12, 1976, he placed a telephone call to the residence of one Peggy Lindsay. A female voice answered. D objected immediately for lack of proper foundation. Zinselmeier then testified that he had spoken with D on at least three occasions (two of which were face-to-face meetings), that he could identify D's voice, and that the voice on the other end of the phone was D's. The court then overruled D's lack of foundation objection. Zinselmeier testified that the first call was followed by a second call during which the same female voice identified herself as Juanita Vitale (D), arranged to sell Zinselmeier dilaudid at a restaurant parking lot, and gave a physical description of herself and the car in which she would go to the parking lot. One hour later D, who matched the physical description given in the phone call and who was riding in the car described in the phone call, met Zinselmeier in the designated parking lot and sold him the substance later identified as dilaudid. D was convicted and appealed. D alleges that evidence about the telephone conversations should have been excluded because no proper foundation was laid.