I am having an issue with calls being transfered to agents from the queue being dead. The agent can't hear the customer and the customer can't hear the agent. When we call the number back that shows up in in Caller ID, the customer tells us they did call and they had hold music and then the call went dead. This seems to be happening with about 1/10 calls but at this point is unpredictable. Any suggestions where to start troubleshooting this one (queues, phones, PRI, Asterisk)? I'm not seeing anything out of the ordinary in the logs when this happens.