Trunk Test Set
Channel: Sarah Autumn
Date: 14/04/2015

Found this at the museum today. 

The red cable going in is -48VDC which is plentiful around the museum. The digital meter is a voltage readout. This test set can send out MF, DTMF, and DP, and in the video, you can see me messing with it a little bit. I was able to find out that it has a manual mode ("Manual Send") and an auto mode ("Auto Send"). In the auto mode, it stores digits, and will send them when you toggle the ON HOOK/OFF HOOK toggle upwards.