Yealink SIP-T21 - Manual (Page 21)

Getting Started
11
If your phone is already installed, proceed to Phone Initialization on page 13 .
This section introduces how to install the phone:
1) Attach the stand
2) Connect the handset and optional headset
3) Connect the network and power
1) Attach the stand
2) Connect the handset and optional headset
Note
3) Connect the network and power
You have two options for power and network connections. Your system administrator will
advise you which one to use.

AC power

Power over Ethernet (PoE)
A headset is not included in the packaging contents. Contact your system administrator
for more information.