Question : Cannot access voicemail on Exchange 2010 from OCS 2007R2. Failure Type 80004005

Hi,

I have just installed a new OCS 2007R2 server on one box that comunicates with my new Exchange 2010. So far all the exchange integration works fine. Only issue is when I try to access my voicemail internally from the client, I get an error and the call does not go through. I searched around for the error I am getting and it points to either a bad certificate (Not sure but the certificate we have on exchange is a certificate from GoDaddy that has all the proper dns entry in it and should be trusted by OCS by default. Also other articles points to a microsoft Patch for Windows 2008R2 that when I try to apply says it does not apply to my systems (Both exchange and ocs). Also I have applied all the patches for OCS per the baseline analyser... This is the error I get from the logs on the OCS error when it fails to get a response from Exchnage:

Log Name:      Office Communications Server
Source:        OCS Protocol Stack
Date:          7/12/2010 9:07:05 AM
Event ID:      14501
Task Category: (1001)
Level:         Error
Keywords:      Classic
User:          N/A
Computer:      OAK-OCS.nvfs1.com
Description:
A significant number of invalid certificates have been provided by remote IP address 192.168.1.15 when attempting to establish an MTLS peer. There have been 20 such failures in the last 3601 minutes.
Certificate Names associated with this peer were
mail.nvfs.org
OAK-EXCHANGE.nvfs1.com
The serial number of this certificate is
04336238F9E582.
The issuer of this certificate is Go Daddy Secure Certification Authority
The specific failure types and their counts are identified below.
Instance count   - Failure Type
30                 80004005
               
               

Event Xml:
<Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">
  <System>
    <Provider Name="OCS Protocol Stack" />
    <EventID Qualifiers="50153">14501</EventID>
    <Level>2</Level>
    <Task>1001</Task>
    <Keywords>0x80000000000000</Keywords>
    <TimeCreated SystemTime="2010-07-12T13:07:05.000000000Z" />
    <EventRecordID>4323</EventRecordID>
    <Channel>Office Communications Server</Channel>
    <Computer>OAK-OCS.nvfs1.com</Computer>
    <Security />
  </System>
  <EventData>
    <Data>192.168.1.15</Data>
    <Data>20</Data>
    <Data>3601</Data>
    <Data>mail.nvfs.org</Data>
    <Data>OAK-EXCHANGE.nvfs1.com</Data>
    <Data>04336238F9E582</Data>
    <Data>Go Daddy Secure Certification Authority</Data>
    <Data>30</Data>
    <Data>80004005</Data>
    <Data>
    </Data>
    <Data>
    </Data>
    <Data>
    </Data>
    <Data>
    </Data>
  </EventData>
</Event>

Answer : Cannot access voicemail on Exchange 2010 from OCS 2007R2. Failure Type 80004005

Issue fixed. Uninstalled OCS 2007R2, re-installed the server with Windows 2008 instead of 2008R2 and now everything is working fine. Issue was most likely with Windows 2008R2 even though Microsoft says that OCS 2007R2 can be installed on 2008R2, I guess it probably requires some trick to get it to work...