In 1950 a new office building was constructed at 510 B avenue, and in 1951 a new automatic drop switchboard was installed that eliminated the need for customers to crank their phone to connect. Ten years later, an automatic dial system was installed, and the old multi-party rural lines were replaced by metallic eight-party lines. These new lines replaced the need for batteries in phones due to a 48 VDC power output from the office to the customer. In 1976 the company completed its evolution from eight-party metallic lines to single-party service, with completely buried outside plant. Having the entire network of service lines underground reduced maintenance by nearly 80%. That same year KCTC bought all long-distance access lines from Bell Telephone System. This meant that KCTC owned the rights to all lines going in and out of its switch, bringing a new level of self-sufficiency and revenue control, as well marking the company’s first steps into global telecommunications.