Summary
Requesting the ability to configure a dedicated line key / DND / BLF button on Yealink T54W (and T4U series) handsets that allows staff to manually toggle the main company phone line between standard business hours mode and the After-Hours IVR menu with a single button press.

Business Use Case & Value
Currently, automatic business-hour schedules handle standard open/close times, but they do not accommodate unpredictable operational changes such as staff taking lunch breaks or leaving early. Having a physical "Night Button" on the front desk or main handsets will allow employees to instantly route incoming calls to the After-Hours IVR menu during these temporary or unscheduled gaps, ensuring no customer call goes unanswered.

Key Requirements & Expected Functionality

One-Touch Toggle: Pressing the designated key on the handset should immediately shift the primary inbound call flow / main trunk routing to the After-Hours IVR. Pressing it again restores normal daytime routing.

Visual Status Indicator: The LED light on the handset line key should provide clear visual feedback (e.g., solid red or blinking when active, off/green when in standard daytime mode) so staff can easily confirm which mode is active.

Handset Compatibility: Must be supportable on standard Yealink T4U/T54W IP desktop phones via standard provisioning (SIP code, Feature Code, or BLF key toggle).