Have a long time customer who got a new managed/sip-based PRI product from their carrier. Its used only for outbound calls. Several times per hour, on multiple channels, they will all the sudden get "Bearer capability not authorized" on an outbound call. The phones display "Access Denied" and the call fails to complete. The carrier insists its not them, but if the customer repeatedly tries the call, it eventually goes through. Anyone seen anything like this or have an idea how to convince the carrier its them?