Yealink SIP-T48G Administrator's Manual page 320

Administrator's Guide for SIP-T2 Series/T19(P) E2/T4 Series/CP860 IP Phones
Procedure
Call hold can be configured using the configuration files or locally.
Configuration File
Local
Details of Configuration Parameters:
features.play_hold_tone.enable
Description:
Enables or disables the IP phone to play a warning tone when there is a call on hold.
0-Disabled
1-Enabled
Web User Interface:
Features->General Information->Play Hold Tone
Phone User Interface:
None
features.play_hold_tone.delay
300
<y0000000000xx>.cfg
Web User Interface
Parameters
Configure the call hold tone and
call hold tone delay.
Parameters:
features.play_hold_tone.enable
features.play_hold_tone.delay
Specify whether RFC 2543
(c=0.0.0.0) outgoing hold
signaling is used.
Parameter:
sip.rfc2543_hold
Configure the call hold tone and
call hold tone delay.
Specify whether RFC 2543
(c=0.0.0.0) outgoing hold
signaling is used.
Navigate to:
http://<phoneIPAddress>/servlet
?p=features-general&q=load
Permitted Values
0 or 1
Integer from 3 to 3600
Default
1
30