I'm having an issue with a few remote agents. We are using Avaya IP Agent 6.0. For the agents to connect to my site they are using a Cisco VPN access (v 5.06). The VPN connects without issue. The IP agent logins into the switch without issue. At first, for both the calling and the called party everything will appear just fine. The called party will see the calling party's Caller ID and the telephone will ring while the calling party will hear a ringing feedback tone at the other end. When the called party picks up the telephone, both the ringing and the associated ringing feedback tone at the other end will stop as one would expect. However, the calling party will not hear the called party (one way audio) and the called party will not hear the calling party either (no audio). This does not happen all the time. Just on occasion.