Configuring OCS Simultaneous Ring with CUCM 7.1

I recently co-authored a Microsoft Next Hop article that gives an introduction to configuring Direct SIP between Microsoft OCS 2007 R2 and Cisco Call Manager 7.1 – see Direct SIP: Cisco Unified Communications Manager 7.1. This post gives addition information about further integrating the systems from an end user perspective.

In addition to the information in the Next Hop Direct SIP article, it is worth clarifying that a new range of phone numbers assigned to Communicator endpoints must be defined in CUCM. This new range needs to be separate from any existing number range used for Cisco desk phone endpoints. For end users who have both a Cisco desk phone and a Communicator client, this means that the same number cannot be used for inbound and outbound dialing. This restriction exists because call routing for Communicator clients in CUCM is achieved by creating a new SIP trunk used solely for Communicator endpoints, and multiple device endpoints cannot share the same number when the call routing is defined on different SIP trunks.

One option to use an existing Cisco desk phone number for Communicator inbound and outbound calling is by implementing the CUCM Simultaneous Ring feature. CUCM will ring the Communicator endpoint for incoming Cisco desk phone calls, and outbound Communicator calls will show the caller-id of the users Cisco desk phone. Simultaneous ring is configured on a per user basis in a user’s Cisco Remote Destination Profile. See the Cisco document “Microsoft Office Communications Server 2007 Enterprise Edition using Direct SIP to Cisco Unified Communications Manager 7.0(1) Simultaneous Ring Feature“. Additional references are included at the end of this article.

The CUCM Simultaneous Ring feature is configured per user on the Cisco IP-PBX, and is accomplished by setting a secondary extension to ring for that user when an incoming call is placed for their Cisco desk phone extension. The next section details the steps to configure it for a user.

Steps to Configure for a User for Simultaneous Ring

#1] Have the user log into the Cisco Unified CM Administration tool. By default this is installed at https://<ccmhost>/ccmadmin/ CUCM can be configured to use the users AD credentials, or separate credentials for users. Here is a screen shot of the login screen:

CUCM - User Login

#2] Select the ‘Remote Destinations’ menu option from the User Options | Mobility Settings menu on the left-hand side of the top menu bar.


#3] Select ‘Add New’ from the top menu. Note: if a user already has an existing Remote Destination Profile that they want to Edit, select the Find button in this menu to list the existing Remote Destination Profiles.  The Find button is highlighted in red in the screenshot below for this step.

CUCM - Adding an RDP

#4] Specify a name for this Remote Destination Profile, and more importantly, the extension to ring. This will be the extension that will ring thru to OCS and ultimately the recipient Microsoft Office Communicator.

CUCM - RDP Settings

Additional Information

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3 comments to Configuring OCS Simultaneous Ring with CUCM 7.1

  • Moto822

    Hi James,

    I am looking to do exactly what you are doing. I have a question if you could assist it would be excellet. My customer still is using Unity for VM. How are you getting calls from OCS backout to Unity? Since the SIP URI will see the user local and not fork to CM?

  • Thanks for the feedback. Yes, having two extensions is less than optimal. There are several ways to improve the situation such as basing the OCS extension on a well known AD attribute, or another piece of data that the user knows (such as their existing DID). OCS still uses a different extension; it just makes it less confusing because the user knows what it is.

    The better solution, which I was close to having work, is to set the OCS extension in CUCM to the users’ SIP address (in the CUCM simultaneous ring options). We just couldn’t get CUCM to format the SIP “To:” to have an “@FQDN_domain”; instead it was presenting the mediation server with a “@mediation_hostname_FQDN”.

    If anyone has cracked that nut, please let me know!

  • James

    Using a differnt extension number for the OCS client makes it confusing for the end user, such as when a user connects to a live meeting as the leader they will have to input their OCS extension instead of their regular extension. The way I worked around this was to assign the user’s DID as their OCS extension and on the CM side assign the extension as their DID prepended with a series of digits. Then CM is configured to strip the series of digits defore it sends it down the trunk to the mediation server. This allows the user have the “same” extension on their Cisco Phone and OCS. This makes a more user friendly experience.

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