Question : SIP and Static

We terminate 20,000 minutes a day in SIP calls over several pbx systems.  One of the systems is an Avaya IP Office 500.  We aggregate all our minutes back to a VoIPSwitch which directs the calls centrally for us.  For some reason only the Avaya is experiencing static.  I would like to know what contributes to static and where should we focus our troubleshooting efforts?

We are presently:

We have moved the SIP to a dedicated 4mb connection for this system thinking it was bandwidth consumption or poor BGP over the Internet.  We have seen utilization on the Internet get to 2mb during peak times.

We have insured that the switches and the router QOS are engaged.  We are running an Adtran 3448 Netvanta on the front of the network.

I am currently at a loss as to what is causing the static.

Answer : SIP and Static

I agree with the first post above.. ..you need to test to see exactly where you get the issues.  If, as you say, its on only the Avaya (and on ALL of the Avaya) connections, then you could start looking at the protocols being used between the systems for transferring the calls.

It could be one leg of the set up is using a different SIP version - or an out of date specification for their 'implementation' of the SIP "standard".  Check compatibility between the different boxes and your VoIPswitch - if the different vendors involved have used slightly different implementations of SIP then this could be part of the issue.