This client makes extensive use of conference calling. The boss is an executive who lives in his car or one of his jets. He will be on the road, call his assistant and says "get so and so on the phone." The assistant rings up the person and then conferences him in to the Big Guy. Then he remains on the call to take notes while muted. Apparently in the last few months the call quality has consistently dropped. The assistant can hear clearly but the Big Guy complains of low speaker volume. They are running 9.1.12 and have a true copper PRI. PRI registers no errors at all over a 10 day monitor. They say nothing has changed. No provider change or changes to the car system.