Lync Phone Edition Updates

When using Lync Phone Edition you might want to upgrade to Lync client on these phones when they become available. The distribution method for this is via the network (of course).

The update process is as follows:

  1. Downloaden from Microsoft update;
  2. Upload the update to the Lync Server;
  3. Approve the update;
  4. Auto install of the client software on the device.

Step 1 is to download the appropriate updates when they are available. For the Microsoft Lync Phone Edition for Polycom CX500, Polycom CX600 and Polycom CX300 they can be downloaded here:, but there are also updates available for Microsoft Lync Phone Edition for Polycom CX700 en LG-Nortel IP Phone 8540 or for Microsoft Lync Phone Edition for Aastra 6721ip en Aastra 6725ip.

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Lync 2010 and Exchange 2010 Unified Messaging

As promised in my previous blog post about Lync 2013 and Exchange 2013 I’ve also been testing this same scenario with Lync 2010 and Exchange 2010. The basics are the same, it’s more or less the GUI that’s different…. Here you go!

UM Language Pack

Download and install the appropriate Exchange 2010 SP2 Language Packs from Exchange Server 2010 SP2 UM Language Packs Continue reading Lync 2010 and Exchange 2010 Unified Messaging

Exchange 2010 UM – A TLS API failure occurred

Recently I was implementing an Exchange 2010 UM server that was not willing to deliver any voicemail messages to the user’s inbox. On the UM server I was several EventID 1423 UMCore error messages in the application eventlog:

Log Name: Application
Source: MSExchange Unified Messaging
Date: 4-2-2013 14:53:25
Event ID: 1423
Task Category: UMCore
Level: Error
Keywords: Classic
User: N/A
The Unified Messaging server encountered an error while trying to process the message with header file "C:\Program Files\Microsoft\Exchange Server\V14\UnifiedMessaging\voicemail\2d831f7a-2a85-40f2-864c-70b4680a118f.txt". Error details: "Microsoft.Exchange.Net.ExSmtpClient.TlsApiFailureException: A TLS API failure occurred. Error = 0x80090301

At the same time I saw lots of EventID 36885 Schannel error messages in the system eventlog of the Hub Transport Server:

Log Name: System
Source: Schannel
Date: 4-2-2013 12:32:56
Event ID: 36885
Task Category: None
Level: Warning
Computer: exhub01.contoso.local
When asking for client authentication, this server sends a list of trusted certificate authorities to the client. The client uses this list to choose a client certificate that is trusted by the server. Currently, this server trusts so many certificate authorities that the list has grown too long. This list has thus been truncated. The administrator of this machine should review the certificate authorities trusted for client authentication and remove those that do not really need to be trusted.

Note. As you may know the UM server records the voicemail message and the voicemail message is sent to the user’s mailbox using the Transport Server.

When looking at the Trusted Root Certification Authorities on the Hub Transport Server it turned out that there were 355 certificates stored here.


This is where things are breaking. The UM server is using TLS to communicate with the Hub Transport Server and during the handshake between the servers the list of root certs is sent. The maximum size of the package being sent by Schannel is only 16KB and the 355 root certificates never fit in these 16KB. Schannel fails, the list of certificates is truncated, resulting in EventID 36885 and the UM server only sees an invalid handshake with a truncated list of certificates and does not want to communicate.

So, the initial entry in the eventlog on the UM server is a result of a TLS issue and important to note, this is not an Exchange problem!

The way to solve this is delete a large number of root certificates from the Trusted Root Certification Authorities on all Hub Transport server. In my environment I reduced the number of root certs to about 85 which is sufficient. When the certificates are deleted the TLS handshake succeeds and the UM server starts sending the voicemails.

The question is how these 355 root certificates ended up in the trusted root store, a newly installed Windows 2008 R2 server in my test environment only reveals 11 certificates in the trusted root store.


Most likely the rootsupd.exe tool has been run sometime ago which updates the list of root certificates on the computer to the list that is accepted by Microsoft as part of the Microsoft Root Certificate Program. Now this is fine on a laptop or workstation, but you don’t want this to happen on your server because it can lead to unpredictable results.

This package however was released to Windows Update and WSUS on December 11, 2012 and was intended for client OS’es only. It also affected servers however and after customer reports the package was set to expired in Windows Update and WSUS.

For more information please check the following knowledge base articles.

Lync 2013 and Exchange 2013 Unified Messaging

In earlier blog posts I’ve written how to install Exchange 2013 and in another series of blog posts I’ve written how to install Lync Server 2013, including connectivity with a SIP trunk provider using a Lync 2013 mediation server.

The last and most exciting part (and least used I’m afraid) is to connect the two platforms into the Exchange 2013 Unified Messaging server role. If a call cannot be answered it’s rerouted into the Exchange server’s UM role where a voicemail can be recorded. This voicemail is then delivered into the user’s mailbox.

Continue reading Lync 2013 and Exchange 2013 Unified Messaging