Check that the QoS usage is consistent by pressing the keypad button sequence Hold Q O S # and using the # key to walk through the menu to verify if the following recommended values are used for traffic priorities:
Layer 2 Audio (802.1p) value = 6.
Layer 3 Audio DSCP value = 40 or 46.
Layer 3 Signaling DSCP value = 40 or 46.
In Communication Manager execute status stationext#.
Run the display ip-interfaces command to find the network region for that procr.
Run the display ip-network-region command to check the QoS settings for the region.
If QoS and IP DiffServ settings in the switches and routers are fine, verify if the voice codec is set to G.729 for calls across a WAN.
If not, turn 802.1p QoS and IP DiffServ tagging on with consistent values across the network by provisioning the recommended values in the switches, routers and IP Telephones. No further steps need to be taken if this solves the problem.
