Yealink SIP-T21 E2 User Manual page 166

User Guide for the SIP-T21(P) E2 IP Phone
If your SIP-T21P E2 IP phone is powered from PoE, ensure you use a PoE-compliant

switch or hub.
Why does the phone display "Network unavailable"?
Ensure that the Ethernet cable is plugged into the Internet port on the phone and

the Ethernet cable is not loose.
Ensure that the switch or hub in your network is operational.

Contact your system administrator for more information.

Why doesn't the phone display time and date correctly?
Check if you have configured the phone to obtain the time and date from the SNTP
server automatically. If the phone fails to connect to the SNTP server, contact your
system administrator for more information. You can also configure the time and date
manually. For more information, refer to
Why can't I access web user interface using the default administrator user name and
password (admin/admin)?
It is case-sensitive, ensure the case is correct.

Ensure the password has not been changed.

If the password has been changed, but the computer remembers the old password,

try to clear the browser cache and try again or select another browser to login.
How to change the user password?
To change the user password via web user interface:
1. Click on Security->Password.
2. Select user from the pull-down list of User Type.
156
Time & Date on page 27.