This is just a guess. I have two boxes on my house. The larger one, the NID, terminates the telco drop and provides an RJ-11 test point. Further back, toward the telco, there is a smaller box (or terminal block) that contains two surge suppressers and the point which is connected to the premises ground.
Back in the old days, this smaller grounding block was all that was installed by the telco to contain the surge suppressers. Once the telco turns the responsibility for the interior wiring over to the homeowner, whenever a technician visits a house, they cut in a NID. When they do so, often times, they leave the old surge suppresser block and grounds in place.
For newer installations, the surge suppressers, grounds and everything are installed in the NID.
Exactly correct. Common practice of telco technicians is to add the NID and leave the old junction pointin place for modifications. New installs get the NID only.
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