detect telephone/intercom ring

Hmm maybe but I see no AC voltage anywhere on this board? The input is DC and I can measure that, that is the screw 3 and 4 (bottom to top in pic) on the blue screw terminal. Screw 5 and 6 measure nothing in either DC or AC voltage. Ive checked everything using a multimeter on both AC and DC modes to make sure. But maybe I am not doing something right, its been 15 years since ive done anything with electronic circuits. Unless possibly that is happening on pins 5 and 6 only when it is ringing or off hook, i have not tested that. This is a pain as I have no one to help me right now and have to run up and down 3 floors to test the darn thing.

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