The Do Not Disturb (DND) feature allows phone users to disable audible
ringing for incoming calls. When DND is enabled, incoming calls do not ring on
the phone, however there is visual alerting and the call information displays,
and a call can be answered if desired. When a local IP phone calls another
local IP phone that is in the DND state, the message “Ring out DND” displays on
the calling phone indicating that the target phone is in the DND state.
Phone users can toggle DND on and off by using the DND softkey in the
idle or ringing call states. A SSCP phone user can toggle DND on or off in the
ringing state only if DND in not already active on the phone. If DND is already
active when a new call comes in, the SCCP phone user cannot change the DND
state by pressing the DND softkey.
If an SSCP phone user toggles DND on during an incoming call, the DND
state remains active for the current call only. If a SIP phone user toggles DND
on during an incoming call, the DND state remains active during the current
call and for all future calls until the user explicitly toggles DND off.
Pressing the DND softkey during an incoming call forwards the call to
the call-forward no answer destination if Call Forward No Answer is enabled. If
Call Forward is not enabled, pressing the DND softkey disables audible ringing
and visual alerting, but the call information is visible on the phone display.
In Cisco CME 3.2.1 and later versions, DND can be blocked from phones
with the feature-ring function. A feature ring is a triple-pulse ring, a type
of ring cadence in addition to internal call and external call ring cadences.
For example, an internal call in the United States rings for 2 seconds on and 4
seconds off (single-pulse ring), and an external call rings for 0.4 seconds on,
0.2 seconds off, 0.4 seconds on, and 0.2 seconds off (double-pulse ring).
The triple-pulse ring is used as an audio identifier for phone users.
For example, each salesperson in a sales department could have an IP phone with
a button sharing the same set of ephone-dns with the sales staff and another
button for their private line for preferred customers. To help a salesperson
identify an incoming call to his or her private line, the private line can be
configured with the feature-ring function. You can disable the DND function on
feature-ring lines. In the preceding example, salespeople could activate DND on
their phones and still hear calls to their private lines.