I have a bcm 450 that we have been troubleshooting with provider for the last past 10 months. They randomly get dropped calls only when they get busy. The calls were only being dropped originally in the acd. Now it happens all the time. When the call gets dropped it usually says normal clearing. The provider says they see no errors. they have sent out several techs to check the pri extension and they have randomly found issues. no details relayed back to customer. The extension is over 1000' and is in a hospital so it bounces from telco closet to telco closet. The provider said they ran a new cat5e extension. But i don't think it goes all the way back to the verizon fiber. I know when we extend circuits we use t-1 cable that both pair is shielded. The system was up to date with its patches back in march. Provider installed 2 different Adtran units at the pbx and the problem got worse. With the Adtran they said they could monitor it better and found nothing. just wondering if anyone has any advice.