Marc F: 400D Central Office or PBX Line Circuit KTU
Marc F: 401A Manual Intercom Line KTU
Marc F: 422B Station Busy Selector KTU
Marc F: 426A
Marc F: 427C
Marc F: 407C Dial Intercom 10-Code Selector KTU
Marc F: 415B Automatic, DC Signaling Private Line KTU
Marc F: 451B Music on Hold KTU