Hello, thanks for your answer, im trying to priorotize the voice packets just inside LAN.

any other suggestion??

thanks again.

You can also use AutoQos if you don't want to manullay configure on all your LAN switches

http://www.cisco.com/en/US/technologies/tk543/tk879/technologies_white_paper0900aecd800a8561_ps6613_Products_White_Paper.html

You just need the below commands to configure autoqos (IP CEF needs to enabled on the switch)

under the interface that the phones are connected to

auto qos trust voip

Your phones should mark the voice packets with DSCP 46 (EF) and Voice signaling with DSCP 26 ( Cisco recommended values)

Could you confirm if this option works with non Cisco ip phones?

we have siemens ip phones

thanks again.

Yes we use it with Avaya. Can your phones mark the packets ?

Yes, the phones mark the packets

Please confirm if switches core and edge must have qos configured or only one of them?

It is always suggested to mark the traffic as close to the source as possible. I believe your IP phones are connected to the edge switches. Though your phones mark the packets & send to the edge switch, the edge switch would wack off the marking & reset it to the DSCP 0.

You need to configure your edge switches for QoS & trust the markings you would be receiving from your IP Phones. Preserve the markings on the trunk uplinks to the CORE.

I am not sure if your phones are capable of marking (siemens), but it does then it's good as you just need to trust the markings. If not, then you can manually set the CoS value on the interfaces.

Hope this helps.