The case of the disappearing tabs

ucspotting — Thu, 14 May 2009 17:28:00 GMT

One of the coolest features of Office Communications Server (OCS) 2007 R2 is the Response Group Service (also known as Automatic Call Distribution – ACD – in telephony world), a technology that’s mostly used in Contact Centers, but that can be applied in many different scenarios…

But the purpose of this post is not to describe the Response Group Service, instead is to discuss some problems I faced when configuring custom tabs in Communicator (custom tabs are the preferred method to sign in to formal groups in Response Group Service).

The problem

I followed the detailed instruction to configure the Response Group Tab. Basically there are 2 steps involved:

Create the custom tab definition file;
Configure Group Policy to apply that file to clients.

Regarding the first step, my XML file consists of the definition of 2 tabs: one for the Response Group, and other for displaying a Live Search box.

<?xml version="1.0"?>
<tabdata>
  <tab>
    <image>https://ptstu-ocs01.demo.local/Rgs/Clients/RgsOcTab.png</image>
    <name>Response Group Tab</name>
    <tooltip>Response Group Tab</tooltip>
    <contenturl>https://ptstu-ocs01.demo.local/Rgs/clients/Tab.aspx</contenturl>
    <siteid>1</siteid>
  </tab>
  <tab>
    <image>https://ptstu-ocs01/images/windows-live.png</image>
    <name>Microsoft Mobile</name>
    <tooltip>Microsoft Mobile Tab</tooltip>
    <contenturl>http://mobile.microsoft.com</contenturl>
    <siteid>2</siteid>
  </tab>
</tabdata>

The second step is also very simple: importing the Communicator R2 Group Policy extension (communicator.adm), and then configuring the setting “Tab URL” (in my case, the value was https://ptstu-ocs01.demo.local/OCTabs.xml).

The problem was that, although all the necessary configuration was in place, there was no sign at all of the 2 custom tabs I had defined previously!

The solution (and troubleshooting process)

In order to solve the problem, I had to change 4 settings.

According to Configuring Custom Tabs in Communicator 2007 R2, the site defined by contenturl must “be located on the intranet, or on a secure or trusted site on the internet” .(particularly if you’re using integrated authentication). The first step to solve my problem was adding http://*.demo.local to Internet Explorer Trusted Sites.
After modifying the Trusted Sites setting there was still no sign of the custom tabs. After a little research on the Internet, I found out that the <contactid> behavior changed in OCS 2007 R2:
“The Communicator R2 client tab functionality has changed from what it was in Communicator 2007. In OC 2007 you could pass the contactID parameter to tabs that were listed at the bottom of the Communicator contacts display. Microsoft has changed the use of tabs in OC 2007 R2 such that you can only display static tabs at the bottom of the Communicator contacts display area. The previous functionality has been moved to the tabs at the bottom of the contact card for each user.”
Since I had <contactid>true</contactid> in my XML file (I omitted the <contactid> element on purpose from my previous listing), this was preventing the Response Group tab from displaying correctly. So, where was the missing tab, you may ask… Again, according to Configuring Custom Tabs in Communicator 2007 R2:
!ELEMENT contactid (“true” | “false”) - Determines whether the tab appears in the contact card. Tabs defined without contactid or with contactid=false will appear only in the Communicator window.Tabs defined with contactid=true will appear in the contact card, and Communicator will pass the selected contact to the defined page. The default value is “false.”
And you know what? Opening the contact card from my user (see the picture below) revealed the link to the tab.
Once I modified the Trusted Sites setting and removed the <contactid> element, the tabs appeared in Communicator, but the content wasn’t being shown:

This kind of error is most often related with proxy settings. Changing the list of exceptions in Internet Explorer advanced proxy settings usually solves the problem.
The last configuration setting I had to change was only affecting a small subset of users that already were using Windows 7 and Internet Explorer 8. This small group still didn’t have the tabs displayed in Communicator. After a long troubleshooting process I finally spotted the problem: in the Tab URL Group Policy I typed a backslash “\” instead of the usual “/” (picture below):
This was the very last issue preventing the tabs from displaying correctly. I guess this is somehow related with stronger security settings in Windows 7 and IE 8.

Connecting Communicator R2 to Exchange UM

ucspotting — Wed, 24 Dec 2008 19:45:19 GMT

Recently, I was doing some tests with Exchange Unified Messaging, but when I tried to connect to Exchange Voice Mail using Communicator R2, I got the following error:

"Incompatible security setting.
The call could not be completed because security levels do not match"

An Exchange UM dial-plan supports three different security levels: Unsecured, SIP Secured, and Secured. The following table shows the differences in terms of Mutual TLS and SRTP for the various security levels.

VoIP Security	Mutual TLS	SRTP
Unsecured	Disabled	Disabled
SIP Secured	Enabled (required)	Disabled
Secured	Enabled (required)	Enabled (required)

When integrating Exchange UM with Office Communications Server 2007, consider the following when selecting the dial plan security level:

Mutual TLS is required between Exchange UM and OCS, therefore the Unsecured level is not an option.
Office Communicator 2007 clients support SRTP (Secure Real-Time Transport Protocol), therefore both Secured as well as SIP Secured security levels can be used. The encryption level that Communicator uses can be set by means of Group Policy or by changing the PC2PCAVEncryption registry key.
If Communicator Phone Edition (aka Tanjay) is deployed, the security level should be set to Secured.

The registry key PC2PCAVEncryption (REG_DWORD) can be used to specify whether encryption is supported, required, or not supported when making and receiving audio and video calls. The supported values are:

0 = Support encryption, but do not require it. Should only be used with the TLS network protocol. (default)
1 = Require encryption. Unencrypted calls are not accepted. Should only be used with the TLS network protocol.
2 = Do not support encryption. Encrypted calls are not accepted.

BTW, if you're playing around with this registry key (or any other), you may find useful to know that Communicator uses the following precedence, when applying settings:

HKEY_LOCAL_MACHINE\Software\Policies\Microsoft\Communicator
HKEY_CURRENT_USER\Software\Policies\Microsoft\Communicator
Office Communications Server 2007 in-band provisioning
Communicator 2007 Options dialog box

Further investigation revealed the following error on Communicator logs:

"SIP/2.0 415 Unsupported Media Type"

After this, it seemed quite obvious that the problem had to do with encryption, more specifically to the SRTP setting. The solution? There are 2 possible ones:

Change the Exchange UM VoIP Security level to "Secured" (it was SIP Secured before).
Create the registry key PC2PCAVEncryption and change its value to 0

One final note: the problem didn't affect Office Communicator 2007, only the R2 client, so we can assume the R2 clients will be more secure than its predecessors.

Rui Silva - UCspotting : Communicator 2007 R2

The case of the disappearing tabs

The problem

The solution (and troubleshooting process)

Connecting Communicator R2 to Exchange UM