Why Can’t I Get A Dial Tone?; Why Doesn’t The Phone Ring?; Why Can’t I Receive Calls?; Why Is My Headset Not Working? - Yealink SIP-T21P User Manual

User Guide for the SIP-T21P IP Phone
How to obtain the MAC address of a phone when the phone is not powered on?
Three ways you can obtain the MAC address of a phone:
You can ask your supplier for shipping information sheet which includes MAC

addresses according to the corresponding PO (Purchase Order).
You can find the MAC address in the label of carton box.

You can find the MAC address from the phone's bar code on the back of the phone.

Why can't I get a dial tone?
Check for any loose connections and that the phone has been installed properly.

For the installation instructions, refer to
Switch between the Handset, Headset (if present) and Hands-Free Speakerphone

to check whether the dial tone is present for one of the audio modes.
If the dial tone exists on another audio mode, connect a different handset or
headset to isolate the problem.
Why doesn't the phone ring?
Check that the ringer volume on the phone. To adjust the ringer volume setting, press
the Volume key when the phone is idle. For more information, refer to
24.
Why can't I receive calls?
Check that the SIP registration with your system administrator.

Check that DND (Do Not Disturb) feature is disabled on the phone. Refer to

Disturb (DND)
Check that call forward is disabled on the phone. Refer to

78.
Check whether the caller number is stored in the blacklist. Refer to

page 38.
Why is my handset not working?
Check that the handset cord is fully connected to both the handset jack on the phone
and handset. Refer to

Why is my headset not working?

Check that the headset cord is fully connected to the headset jack on the phone.

Refer to Phone Installation
Check that the headset mode is activated. Refer to

Activation/Deactivation
120
on page 75.
Phone Installation on page 11.
on page 11.
on page 45.
Phone Installation on page 11.
Call Forward
Headset Mode
Volume on page
Do Not
on page
Blacklist on