quality voice problems using CCME

[mmartel]

Hello:

I have installed a CCME voice network, I use 7940 IP Telephone and ATAs. The equipments are connected to a Switch Cisco 3550, have power on line feature and IP Phones are configured to 100 Mbps full duplex. Some users have quality voice problems.

What is the minimum cable category that cisco suggest to voice?

Is the speaker mode full duplex or half duplex?, may be this can be the problem.

Is there a way to priorize traffic voice into the switch, the connection is shared between PC an phone?

regards

[thisisshanky]

Is this happening for calls between ip phones or to the PSTN ?? 100 Mbps is recommended which would be Cat5 or better.

The packets coming in from the PC are zeroed out on their TOS bits by the IP Phone, while its own packets are set to TOS value of 5 and send out..This is achieved using the following command..

switchport priority cos extend 0 (this is the default). So the Phones packets should have higher priority over PC packets.

http://www.cisco.com/en/US/products/hw/switches/ps628/products_configuration_guide_chapter09186a00800d84c0.html

Try removing the PCs from the phones of users having voice quality issues and see if that really is the culprit..