Hi Steven,
f-Feature ring is really a special "ring cadence" that is easily identified from other lines that ring on a multiline phone. When used in conjunction with no dnd feature-ring it allows a user to set their phone in "Do Not Disturb" but still have this special line (marked with the "f" feature ring option) ring :)
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Single character that denotes the characteristics to be associated with this phone button. Valid entries are as follows:
: (colon)-Normal ring. For incoming calls on this extension, the phone produces audible ringing, a flashing icon in the phone display, and a flashing red light on the handset. On the Cisco IP Phone 7914 Expansion Module, a flashing yellow light also accompanies incoming calls.
b-Beep but no ring. Audible ring is suppressed for incoming calls, but call-waiting beeps are allowed. Visible cues are the same as those described for a normal ring.
c-Call waiting. Provides call waiting for secondary calls to an overlaid ephone-dn. See also the o keyword.
**f-Feature ring. Differentiates incoming calls on a special line from incoming calls on other lines on the phone. The feature-ring cadence is a triple pulse, as opposed to a single pulse for normal internal calls and a double pulse for normal external calls.
Feature Ring (f)
A feature ring is a third type of ring cadence, in addition to the 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). A feature ring is a triple-pulse ring. The purpose of associating a feature ring with a line button is to be able to identify from a distance a special line that is ringing on a multiline phone.
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.
SCCP: Blocking Do Not Disturb
To block DND on phones that have buttons configured for feature ringing, perform the following steps. DND is enabled by using the DND soft key on Cisco Unified IP phones that support soft keys.
SUMMARY STEPS
1. enable
2. configure terminal
3. ephone phone-tag
4. no dnd feature-ring
Example:
Router(config-ephone)# no dnd feature-ring
Allows phone buttons configured with the feature-ring option to ring when their IP phones are in do-not-disturb (DND) mode.
5. end
In the following configuration example, when DND is activated on ephone 1, button 1 will ring, but button 2 will not.
ephone 1
button 1f1
button 2o10,11
no dnd feature-ring
http://www.cisco.com/en/US/docs/voice_ip_comm/cucme/admin/configuration/guide/cmednd.html
Hope this helps!
Rob
