Yealink SIP-T21 E2 Administrator's Guide

Administrator’s Guide for SIP-T2 Series/T19(P) E2/T4 Series/T5 Series/CP860/CP920 IP Phones
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Early Media
Early media refers to media (e.g., audio and video) played to the caller before a SIP call is
actually established. Current implementation supports early media through the 183 message.
When the caller receives a 183 message with SDP before the call is established, a media
channel is established. This channel is used to provide the early media stream for the caller.
180 Ring Workaround
180 ring workaround defines whether to deal with the 180 message received after the 183
message. When the caller receives a 183 message, it suppresses any local ringback tone and
begins to play the media received. 180 ring workaround allows IP phones to resume and play
the local ringback tone upon a subsequent 180 message received.
Procedure
180 ring workaround can be configured using the following methods.
Central Provisioning
(Configuration File)
<y0000000000xx>.cfg
Configure 180 ring workaround.
Parameter:
phone_setting.is_deal180
Web User Interface
Configure 180 ring workaround.
Navigate to:
http://<phoneIPAddress>/servlet?
p=features-general&q=load
Details of the Configuration Parameter:
Parameter
Permitted Values
Default
phone_setting.is_deal180
0 or 1
1
Description:
Enables or disables the IP phone to deal with the 180 SIP message received after the 183
SIP message.
0-Disabled
1-Enabled
If it is set to 1 (Enabled), the IP phone will resume and play the local ringback tone upon a
subsequent 180 message received.
Web User Interface:
Features->General Information->180 Ring Workaround
Phone User Interface:

Yealink SIP-T21 E2 Specifications

General

Brand	Yealink
Model	SIP-T21 E2
Category	IP Phone
Language	English