Telephony, June 19, 1920, page 74:

Radio  Telephone  Exchange  for  Avalon  Island,  Calif.

    The first commercially operated wireless telephone exchange in the world, according to officials of the Pacific Telephone & Telegraph Co., will soon be operated from Avalon, Catalina Island, Cal., to the mainland, a distance of about 30 miles.
    The city of Avalon granted the telephone company's petition for leave to establish a local service on the island, with wireless connections to Los Angeles and other points. The telephone company's announcement said that an ordinary exchange would be installed at Avalon, and that messages from that point to the mainland would be handled by wireless, without relaying.
    A subscriber to in Los Angeles, they said, would call central in the usual way, and the person he talked with in Avalon, would answer an ordinary telephone, but the distance between the island and the shore would be bridged by the use of wireless. Heretofore Catalina Island has been dependent on a wireless telegraph station and airplane and boat mails.