this is something weird I have never seen. CB Radio interference on a BCM50 with PRI. Several sets in the building report hearing local CB radio traffic on a daily basis. thought it might be the lines and cross talk, but got on site to find out its a PRI. All the sets are T7316E series.

There's a filter for that, or at least there used to be. Had a client where Bell had to install these on the line to suppress the interference. They looked something like a DSL filter.