A quick and crude video of a vintage Stromberg-Carlson XY PBX undergoing restoration in the California high desert. (This would only be of interest to vintage-phone phreaks; don't say I didn't warn you.) See www.youtube.com for more on this system. The shot opens next to the XY line-finders as a test set is taken off-hook. The line-finder hunts for the station line that has been taken off hook, and provides the connection from the calling extension to a matching XY connector switch. Next, a view of the line-finder allotters (rotary switchs just to the right). The allotters assign a line-finder out of the bank to service the next dial tone request. As the phone is taken off hook again, you can just barely make out the allotter (1 of 2) spinning around to assign the next line finder to be used. Around the back side, the connector (not to be confused with a washer-dryer) is seen in operation while dialing station "15". This rings the white el-cheapo phone ("Damn phone!"). Last, the XY connector switch is shown as a new call is started and the tie-line access code "8" is dialed. The dial tone is generated by three vacuum-tubes. I think they are 50V6s; a version of the popular 6V6 but with 50 volt filaments, supplied by 48V station battery (probably used as B+ too). The rhythmic clickity-clack you hear when the phone is taken off hook is the interrupter. This is a series of cams on a motor driven shaft that operate various switches. These provide the on-off cycles for ringing <b>...</b>