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Level 10
Level 10

Callmanager 6.0 and higher

  1. Go to Call Routing > Intercom > Intercom Partition and create a new partition.
  2. Go to Call Routing > Intercom > Intercom CSS and create a new CSS that containst the partition created above.
  3. Go to Call Routing > Intercom >Intercom Directory Number and create 2 different directory numbers that we will use to communicate. Also associate the CSS created above, and choose a Default Device to which you will assign this particular number.
  4. Go to the first phone we will configure under Device > Phone and modify the phone button template as shown below:button-template-config.jpg It might be necessary to remove one of the options from the left square to make room for the new option; just select an unwanted option and clic on the arrow pointing down to the bottom square. Now, on the right square choose "Intercom [1] - Add a new Intercom", and click on the arrow pointing left to the left square. The option might appear on the left, at the bottom of the list.
  5. Save the changes everywhere and reset the phones or apply configuration (depends on the Callmanager version).
  6. Click on the Intercom option at the left side of the phone configuration page, this will take you to the Intercom Directory Number page.
  7. Look for the "Speed Dial" field, and input the target number. This is the Intercom DN that will go off-hook in speaker mode when you press the Intercom number we are currently configuring. ***NOTE*** If you do fill the Speed Dial field, when pushing your Intercom DN button will open the line and prompt you to enter any Intercom number. Only an Intercom number will be accepted, any regular DN won't work and most likely will ring busy if it doesn't perfectly match an Intercom number you don't know about.
  8. Do the same configuration to the other IP Phone assigning it the second Intercom DN we created.
  9. With the correct CSS and partitions, and after filling the Speed Dial field on each device, we should now be able to press the button and go off-hook with the other device. You can choose if you want your Intercom line to go off-hook in headset mode or in speaker mode from the line configuration page.


  • The following models support the feature in both SCCP and SIP mode:


The 7931 only supports it in SCCP.

  • One Intercom DN, say 200, can't be associated to multiple devices, or in other words, it doest allow sharing. You will get an error similar to "Update failed. Intercom line is not shareable"
  • Intercom calls do not follow a coverage path.
  • Hold - The system does not allow intercom calls to be placed on hold.
  • Call Forwarding - The system does not allow intercom calls cannot be forwarded.
  • Transfer - The system does not allow an intercom call to be transferred.
  • iDivert - The system does not allow an intercom call to be diverted.
  • Call Pickup/Directed Call Pickup - The call pickup groups do not include intercom calls.
  • DND - Intercom overrides Do Not Disturb (DND).
  • If sufficient bandwidth does not exist, the intercom call fails.
  • If two intercom calls are directed to a target, the first one goes through; the second fails with a busy tone.
  • Barge and cBarge - Intercom does not work with Barge and cBarge features.
  • Conferencing - The system does not allow intercom calls to be conferenced.
  • When an active call is being monitored or recorded, the user cannot receive nor place intercom calls.

Related information:

For more details about the Interactions and Restrictions, please follow the Features and Services Guide pertinent to you Callmanager version:

This feature doesn't provide a voice message broadcating capability (sometimes called paging).

Note: Generally, on Call Manager 4.x the  Intercoms were configured with a speeddial on the Admin phone set to ringdown

to the auto answer DN on the Manager phone. On CUCM 6.X and above it would be a speeddial to a number for example lets

Managers Number be 1000 then on the Admin's Phone add a DN 1000 with auto answer for the manager.

For more details refer Intercom

Callmanager 4.x and below (Document K62352022 applies to these versions)

Cisco CallManager does not have a dedicated intercom feature. However, you can use the Auto Answer feature in Cisco CallManager. Activatving this option or button causes the speaker phone to go off hook automatically when an incoming call is received.

To configure Auto Answer, perform these steps:

  1. On the Cisco CallManager Admin page, go to  Device > Phones > Select the Extension. Select Enable the Auto Answer feature.
  2. Choose one of these options to activate the Auto Answer feature for the  directory number:       

    • Auto Answer Off
    • Auto Answer with headset
    • Auto Answer with speakerphone (intercom)

For more information refer to Cisco IP Phone Configuration.


Many sites with an existing PBX also have a paging system, allowing users to call  an extension on the PBX that forwards the audio broadcast to overhead  loudspeakers. This concept is useful in workshops, parking lots, and open plan  areas where a called party is not near a telephone handset. PBX manufacturers  may provide dedicated line cards that interface with external paging amplifiers.

The Cisco CallManager needs the Cisco 2610 router to be configured as an H.323  gateway device. The extension number for the paging port is defined under the  Cisco CallManager Route Pattern configuration page, pointing to the Cisco 2610  H.323 gateway.

When the number for the paging system is dialed, a VoIP call is made between the  IP handset to the E&M port on the gateway router. The voice port goes off hook.  This is indicated by the E lead on pin 7 going from open circuit to closed  circuit (with respect to the ground on pin 8). This off hook condition activates  the pager system's control input, and the audio is sent on pins 4 and 5 of the  voice port

For more information, refer to Using Analogue E&M ports to interface to Overhead Paging Systems.


Excellent document.......worked like a charm on CUCM9.1.....i used a CIPC and 7945......thanks Geevarghese Cheria

Chandra Sekar
Level 1
Level 1

Very Crispy Document. I missed the Speed-Dial part of the configuration. Thanks very much. Geevarghese

Sourabh Mudgil
Level 1
Level 1

Very good document.

But, one very important thing missing here is, "Default Activated Device" configuration on the Intercom line.

We must associate the phone's MAC on this field in order to get the Intercom line on the physical phone otherwise it would be blank with no functional Intercom line.



Level 1
Level 1

Yes i struggled at first, has anyone tired the new Singlewire Paging platform, its now layerd onto Call Manager, you can now deploy cisco and singlewire enabled intercoms. A good sell to the End User being: your SIP Intercom will also double as a paging IP Speaker, accpeting simultaneous sip and priority based multicasting.

Very Nice Document!!!

Tom W.
Level 1
Level 1

Is step 4 required? Can't we just use a regular Line DN line instead of having to modify the phone button template?

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