Yealink SIP-T48G Administrator's Manual page 221

2. Select the desired value from the pull-down list of RFC 2543 Hold.
3. Click Confirm to accept the change.
To configure call hold tone and call hold tone delay via web user interface:
1. Click on Features->General Information.
2. Select the desired value from the pull-down list of Play Hold Tone.
3. Enter the desired time in the Play Hold Tone Delay field.
4. Click Confirm to accept the change.
Configuring Basic Features
207