The Full form of MTS is Mobile Telephone Service. The MTS was a pre-cellular VHF radio system that linked to the PSTN (Public Switched Telephone Network). MTS was the radiotelephone which was equivalent to the land dial phone service. It was assisted by the operators on both the sides. So, to make a call from the land line to the receiver, call will be routed through the mobile operator, who would divert the call to the receiver. Similarly, if a person has to make an outbound call, the mobile operator will first dial the number and then the call will be placed.
The MTS (Mobile Telephone Service) was one of the earliest mobile telephone standards. This service originated with the Bell System, and was first used on June 17, 1946 in St. Louis. The original equipment weighed 36 kg (80 pounds), and there were only 3 channels initially for all the users in the metropolitan area, but later on more licenses were added bringing the total to 32 channels across 3 bands. This service was used in large portions of North America at least into the 1980s. Motorola communications equipment on 2nd October, 1946, carried the first calls on Illinois Bell Telephone Company’s new car radiotelephone service in Chicago.