Lifesize spam calls or unknown SIP calls
Option 1) If only SIP calls are being spammed then you can disable SIP in the Admin settings of the codec.
Option 2) In Admin setting of codec create a white-list of IP's. This would remove all inbound traffic to your codecs except what is programmed into the codec. However you would have to have all IP devices that can connect to the codecs, each codec, your iPads and anyone else who is supposed to be able to call in, set to a static IP address and then program them into the codec. Or at least if you know the inbound IP you can add it to the white-list.