This article originally appeared on ABACUS Smartphones have rendered public phone booths mostly obsolete, but Shanghai has found a new way to revitalize these remnants from the past -- by turning them into mini 5G base stations. China Telecom Shanghai, a phone service provider, is installing 5G transceivers and other equipment in a phone booth located in the city's Jingan district, Liberation Daily reported . There are currently more than 5,400 phone booths in the city, and the goal is to convert dozens of them into small cells to support the city’s expanding 5G network. Last year, China said it planned to introduce millimeter wave frequencies for 5G use. These waves are in a different radio spectrum from bands traditionally used by mobile services, which means higher bandwidth and faster speeds. But higher frequency waves also have shorter wavelengths, which means they are easily blocked by walls and buildings. One solution is to install a large number of mini base stations across the city to form a tighter 5G network. It’s not the first time that Shanghai has put old phone booths into new use. Some booths already broadcast Wi-Fi signals.