While we are on video conference calls a call comes into our Group 700 unit from unknown ID 100 and we can not cancel the call or answer it. What is this and how do we stop it?
congratulations - you are likely getting a sip / hack attack aka: sipvicious attack
if you have a fire wall you can block the ip address it is comming from to start
if you have an sbc - you can kill the incomming invites fron 100
a packet trace on port 5060 will show you more information