What is the primary method for device authentication in a VoIP network?

A.
IP address

B.
MAC address

C.
SIP address

D.
IP and MAC address

Explanation:

The primary method for the device authentication of IP phones is the MAC address. If a phone with an unknown MAC address attempts to download a network configuration from the call-processing manager and it has no knowledge of the IP phone’s MAC address, then that IP phone will not receive a configuration assuming automatic registration has been disabled.
Reference: Cisco Courseware p.9-24