Hello! Now I want to share with you some tips on configuring LCS and its client  Office Communicator to originate VoIp calls to a Cisco SCCP IP Phone or conventional PSTN phones through a Cisco Call Manager 4.1 SR3.


Many companies setup Cisco Telephony over IP environments and don’t know they can use Office Communicator and LCS 2005 to place calls to the VoIp and PSTN clouds just using the already in-place Cisco infrastructure.


I mean, the companies do not need a special gateway just to make VoIP and PSTN calls from Office Communicator using their in-place Cisco Call Manager 4.1.


In fact, they still need a gateway if the goal is to make signaling (3PCC/CSTA) integration.


Actually I have a customer using Cisco Call Manager 4.1 to place VoIP calls to all their IP and PSTN phones using the integration already made between the CCM 4.1 and the corporative PBX.


Before to start with the configuration steps I’d like to list what will work after the setup:


  • Calls can be placed from LCS (Office Communicator) to another VoIP phone “connected” through CCM.
  • Calls can be placed from LCS (Office Communicator) to PSTN phones through CCM. 

What will not work?


  • Transfer, conferencing and call forwarding from Office Communicator (LCS) side. [Requires a CSTA/3PCC gateway]

First let’s check the network topology.




Now the steps.


  1. Open the Microsoft Office Live Communications Server 2005 MMC administrative console.
  2. Expand the forest node, the domain node and the Live Communications Servers and Pools node.
  3. Click with the right button on the LCS Pool and create an outbound static route pointing to the Cisco Call Manager with the following information:
    • User: *
    • Domain: <LCS POOL FQDN>
    • Next Hop IP address: the IP address used by Cisco Call Manager
    • Next Hop Transport: TCP
    • Port: 5060
    • Phone URI: Checked
  4. On the Host Authorization Tab, include the IP of the Cisco Call Manager as a Authorized Host. Use the following options:
    1. Server IP Address: the IP address used by Cisco Call Manager
    2. Settings:
      • i.      Throttle as Server: Checked
      • Treat as Authenticated: Checked
  5. Open the CCM Administration web page and create an incoming partition (probably it will already have one).
  6. Create a new SIP Trunk with the following options:

Device Information


    1. Device name: LCSSIP
    2. Device Pool: Default
    3. Call Classification: Use System Default
    4. Media Resource Group List: Select appropriate list.
    5. Location: None
    6. AAR Group: None
    7. Media termination point required: Checked
    8. Destination address: the IP address used by LCS
    9. Destination port: 5060
    10. Incoming port: 5060
    11. Outgoing transport type: TCP
    12. Preferred Originating codec: 711ulaw

Call Routing Information


a.      Significant Digits: All

b.      Connected Line ID Presentation: Default

c.      Connected Name Presentation: Default


  1. Create a Media Termination Point using the Add Media Termination Point on the CCM web administration.

You also need to setup a registry key (manually or using Group Policies) to enable the PC2Phone functionality on your Office Communicator.



On the COMMUNICATOR.ADM template this configuration is named "Enable Computer to Phone Calls".


Now go to the Office Communicator and just type the phone number on the Find box, click on Call to place Voip or PSTN calls through the CCM 4.1. You will also notice that the combo box on the side of your contacts is now enabled.


Regards, Cris.

This posting is provided "AS IS" with no warranties, and confers no rights.