That inspired me to try other new products, like the first wireless telephones, the first telephone answering machines, the first air purifiers, and eventually this led to a full color catalog of new technology products, and later, 200 retail stores.

FORBES: Richard Thalheimer's Entrepreneurship Advice

On its website, PhoneTel says Henderson became the apprentice of Japanese inventor Dr. Kazuo Hashimoto in 1993, credited with producing the first telephone answering machine.

FORBES: AT&T Says Cellfone Patent Invalid Over Lies