Question : Problem: Poor voice quality with 3com router 3016 and 3com 4400 switch from NBX

I need to prioritze the voice traffic from my 3com nbx system across a p2p t1to a 3com 3016 router which connects to a 3com 4400 switch.  How do I do it?

Answer : Problem: Poor voice quality with 3com router 3016 and 3com 4400 switch from NBX

Virtually all modern switches have at least two (while top notch ones have four) priority queues, usually done in hardware, so, as far as you are implementing voice solution across whole network, you have to setup all of them to prioritize voice traffic. This will help you to get rid of cognestions etc. at layer 2.

Having NBX phones and Call processor in different subnetwoks divided by routers demands setting up prioritisation at layer 3 (IP). These are general guidelines.

So, you should decide which switches and routers are involved in passing voice traffic and do some changes in their settings regarding QOS. If I were you, I'd implement it on all the switches and routers across your network whether they pass voice traffic at the moment or not.