Yealink T48S User Manual page 6

Power over Ethernet
With the included or a regular Ethernet cable, the SIP-T48S IP phone can be powered from a PoE-compliant
switch or hub.
To connect the PoE:
1. Connect the Ethernet cable between the Internet port on the phone and an available port on the in-line
power switch/hub.
If in-line power switch/hub is provided, you don't need to connect the phone to the power adapter. Make sure
the switch/hub is PoE-compliant. The phone can also share the network with another network device such as a
PC (personal computer). It is an optional connection. Important, do not unplug or remove power to the phone
while it is updating firmware and configurations.