Hello,

I have a remote network that connects to our office through MPLS. Recently we added some Nortel IP 2002 phone at remote location that connects to a Nortel CS 1000 via MPLS. Usually the voice calls work normal. But there has been around 2/3 instances per day when remote caller can hear me, but I can't hear him. It happens in the middle of a call. Phones are connected to a Cisco 3560 PoE with Voice Vlan 101 and data vlan 1. Switch ports are in access mode. Switch is connected to a Cisco 2801 via trunk port and the router interface is configured with dot1.q. Currently i have a class based fair queue on the router for priority with 60% bandwidth to voip and everything else fair-queue out of a T1 connection. At my end I have 6Mbps of MPLS with similar priority for VoIP. Could someone help to find why some of the calls are having this issue? Thanks.

When you say one way, is it safe to assume one way audio? If so, are you using NAT anywhere in the mix? If so, this may account for it. You'd need to configure your phones to use a STUN server

perl -e 'print $i=pack(c5,(40*2),sqrt(7600),(unpack(c,Q)-3+1+3+3-7),oct(104),10,oct(101));'