The Service was launched in 1937, being timed to the 20th October Revolution anniversary celebrations. The first announcer who sound-recorded the exact time voice service for the Muscovites was Olga Vyssotskaya. She was selected from amongst several broadcaster contenders comprising Yuriy Levitan (most prominent radio announcer of the '40s-'80s of the XXth century in this country). Initially, the announcers had to insonify each minute of the day, and the record was replayed on a twenty-four hours' basis. At present, Olga Vyssotskaya's voice record for the "talking clock" is kept at the Moscow City Telephone Network Museum.
In 1970, the equipment of the "Exact Time of Day Voice Service" was upgraded. The hardware with the phonogram that was in operation for thirty years continuously was replaced with magnetic tape answering machines. The phonograms of new answering units were recorded on the disks with two independent sound tracks - the hour track and the minute track, which were engaged alternately at the moment of the needful information playback. The error rate of the primary clock that operated the answering machine was 2 seconds a month only, and one and the same voice information could be replayed from the clock 10 times during one minute.
In the '90s of the 20th century, the "Exact Time of Day Voice Service" stood yet another upgrading, i.e. reswitching to the digital equipment. For the space of 65 years of its operation, the PJSC MGTS "Exact Time of Day Voice Service" was provided free of charge to all the Moscow citizens. Presently, about 3 million people make use of the "talking clock" daily, and it is a service in the highest demand of the public out of the total range of directory inquiry services PJSC MGTS offers its subscribers and customers.