Yealink SIP-T48G - Manual (Page 109)

Basic Call Features
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The touch screen indicates that the call is on hold.
The phone will beep softly every 30 seconds to remind you that you still have a call on
hold.
To resume a held call:
1. Press or tap the Resume soft key.
Multiple Calls on Hold:
If multiple calls are placed on hold, do one of the following:
- Tap the desired call, and then tap the Resume soft key to retrieve it.
- Tap the desired call, and then tap the corresponding line key to retrieve it.
You can use DND to reject incoming calls automatically on the phone. Callers will
receive a busy message.
You can enable/disable DND for the phone system, or you can customize DND for each
or all accounts. Two DND modes:

Phone (default): DND is effective for the phone system.

Custom: DND can be configured for each or all accounts.
You can receive incoming calls from authorized numbers when DND is enabled.
To configure the DND mode via web user interface:
1. Click on Features->Forward & DND.