A type of electromechanical circuit switch developed by the Bell System for use in large metropolitan areas, where it was felt that the more conventional step-by-step (SxS) would not scale properly. As the first common control switch, the panel switch used a store-and-forward technique in which the digits dialed by the end user were stored in a register, or temporary buffer. Once the complete telephone number had been dialed, the register sent the dialed digits either to a translator for translation into routing instructions, or directly to the sender, which then sent the appropriate dialed digits across a trunk or to local switching equipment. A panel switch was so called because the line selector system operated on a system of ladders. As a selector received each dialed number, it would rise up a ladder in a vertical panel mounted on a frame. Panel switches were first placed into service in the 1920s, through the 1930s, and remained in service until the late 1970s, at which point they were replaced by electronic common control (ECC) switches. See also ECC and SxS. PANS (Pretty Advanced New Services, Pretty Advanced Network Services, Peculiar And Novel Services) A term that appeared in the 1970s to distinguish new PSTN services from POTS (Plain Old Telephone Service). PANS includes custom calling services such as caller ID and name ID, call waiting, conference calling, and three-way calling.The term really never caught on. See also POTS and PSTN.