Been down this road more than once. The static is coming from the TELCO. Remember, in the C.O they break out in a channel bank. AND SOMETIMES they go through 1 or more intermediate points where they are broken down to audio in one channel bank and then put through another channel bank to a different span. Just because they come into the building on the same span, doesn't mean they got all the way there on the same span! Had a span in Texas that had various problems on various channels. The Telco tech that finally got to the motel had a complete circuit drawing. What a mess. The channels all broke down to audio at least twice on the way from the C. O. to the Motel. And they used at least 3 different paths to get to the final span into the motel. Problems were mostly dialing permission variations, but 2 channels had mild static and 1 had NO AUDIO at all. I finally got action when I itemized the specific problem(s) with EACH channel. The first 2 tries were "Channels have screwed up dialing permission and intermittent static". Of course they checked the first channel and it was fine.

When I was young, I was Liberal. As I aged and wised up, I became Conservative. Now that I'm old, I have settled on Curmudgeon.