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One of the new OCS 2007 R2 features is the Address Book Query service.   One of the primary benefits of this feature is to allow COMO clients to search the OCS Address Book over the Internet (using HTTPS) without having to download the Address Book files.   For more information, you can refer to the following Microsoft TechNet links.

According to the Microsoft TechNet link,, you must use an IP address to publish (or reverse proxy) the OCS Address Book to enable Office Communicator Mobile clients to search the Address Book over the Internet.  The link also provides good information how to set up and secure OCS, including publishing the OCS Address Book, using an ISA 2006 Server.

Instead of using an ISA Server, we chose to use our F5 BIG-IP devices to provide connectivity from the Internet to our OCS 2007 R2 infrastructure for our COMO devices.

After successfully setting up our F5 BIG-IP configuration, we were able to use our COMO devices to connect successfully to OCS from the Internet.   We could see presence information, see our groups and contacts, and send instant messages to other users.  However, when we tried to search for a contact using the Find/Add option, we would get a Search failed or was canceled.  Please try again. error message on the device.


Due to Microsoft’s reverse proxy requirements for external Address Book searches, we did some additional research and learned a few things through trial and error how to set up F5 BIG-IP devices as a reverse proxy to allow users to search from their COMO devices.  If you are using F5 BIG-IP devices in your environment, here are a few tips to help you get started to enable external Address Book searches for your COMO devices.

You will need to review the F5 Deployment Guide: Microsoft Office Communications Server 2007 R2 (BIG-IP 10, 9.x) to get started.

Here are a few things that we learned through trial and error that you need to be aware of as you set up your implementation.

1) Publish your external certificate in txt format on the F5 device.
2) Build one virtual configuration for port 444, 5061 and create a tcp profile with an idle timeout value of 1200 seconds (according to the document)
3) Build one virtual configuration for port 443 and create a tcp profile with an idle timeout value of 1200 seconds (according to the document)
4) Create a client side SSL profile for the SSL certificate and apply it to the virtual (the reason we had to use the SSL certificate was because the certificate on our OCS front-end server did not match the URL the COMO device uses)

Once we configured everything accordingly using the above information, we were able to do external Address Book searches from our COMO devices.

Posted on Friday, October 23, 2009 3:33 PM | Back to top

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