When doing a call simulation and using an Avaya VoIP phone as the IP destination, the phone will firewall itself and block a large portion of the simulated VoIP packets that we send it. This is Avaya’s design to protect the phone against denial of service attacks from outside sources.
As a result, if you do a call simulation to an Avaya phone, it will show 80% to 90% loss. It is thus advised to test to the upstream switch from the VoIP phone instead.