 The volume of the ringer gradually built up over the first few cycles.There is a volume control in the base of the telephone with 'loud', 'medium' and 'soft' settings (a silent setting was achieved by slackening off a screw on the tone ringer board inside the phone).Production of the new telephone commenced in 1965 by STC, and an initial quantity of 1000 was offered to customers on a selective trial basis in the London North West Telephone Area in the same year.