C. Consequence of encrypting communication
Since the signalling encryption already takes place on the end devices, customer edge routers are unable to trace signalling and therefore, dynamically open and close ports for media streams.
As a consequence, a wide range of UDP ports must be opened for outgoing traffic; all media streams must run over the Internet connection.
Once encryption is activated for a customer, all devices approved for encryption will automatically be switched to this setting. Billing will always include only the encryption compatible devices.