An IT technician is tasked with installing a new VoIP phone system in an office environment. The phones require a power source and the technician wants to use the network wiring to provide both data connectivity and power. Which of the following PoE standards should the technician ensure the network switches support to provide up to 15.4 watts of power to each connected VoIP phone?
802.3bt
802.3at
802.3ad
802.3af