I have a small call center with around 350 seats, everyone has 4621 and 4610 phones. Everyone has a Avaya/Plantronics AWH-55 Headset connnected to there phone using the EU24 port and the headset button. Sometimes when they press the headset button to answer the call, it will light the headset light, connect the call and then hang up the call. This is randomly happening on all most all of the phones. Any ideas?