Abstract: A telephone station identification system arranged to identify directory numbers assigned a plurality of telephone stations concurrently served by telephone offices of a switching system. Groups of telephone office lines are asynchronously scanned to detect ones of the lines selectively coupled to served telephone stations. Apparatus identifies telephone offices serving telephone stations by applying signals during a first clock sequence to scanned office lines coupled to telephone stations and registering ones of the signals as an identity of the telephone offices serving the telephone stations. The apparatus selectively reapplies the signals during a second clock sequence to each scanned call handling office line within an identified telephone office and sequentially generates the directory number digits assigned each telephone station currently served by the identified telephone offices.