Skype For Business SDK Prerequisites

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It could be a good idea to drive Skype for business 2016 from a c# application. There a couple of use cases:

  • Send automatic notifications from the application to some other people (like an alert sent to an administrator for example)
  • Reply automatically to incoming messages
  • Simulate a user scenario to test Skype for business service (connection - send message to a group of people - disconnect)

To develop application driving Skype for business, at some point you have to download:


For your application to be run correctly you have to setup a couple of registry keys. Once Skype For Business is installed, when you launch it, skype process starts with a nice user interface asking you to login.

Let's close this user interface. Every application which wants to drive Skype For Business must be sure Skype is setup in the : UISuppressMode, e.g. : No User Interface !

To achieve that, 2 registry keys must be set :



While playing with c# Skype SDK, I have discovered an issue when the application tried to disconnect.

Skype has a weird behavior which was a kind of impediment in my use case. I had a couple of credentials to test indefinitely, I mean connections with different users to skype.

When you diconnect from Skype, credentials are not cleared at all, they are cached. The next time you try to initiate a connection, those credentials are reused even if you specify other credentials.

I spent a lot of time to figure out what was my problem. When I found it, I looked for a way to clear the cache credentials and I have a found a nice API :

  • ForgetMe :

Deletes SignIn credentials and cached data

Nice ! Lets use it ! AND ? .... I have a really nice exception :

Unable to cast COM object of type 'Microsoft.Office.Uc.SignInConfigurationClass' to interface type 'Microsoft.Office.Uc.ISignInConfiguration2'.
This operation failed because the QueryInterface call on the COM component for the interface with IID '{61CE9972-C619-4A88-A5D1-D2DFBCD4D2A1}' failed due to the following error:
      No such interface supported (Exception from HRESULT: 0x80004002 (E_NOINTERFACE)).

00039; 2016/04/13 13:17:56 204;                 at System.StubHelpers.StubHelpers.GetCOMIPFromRCW(Object objSrc, IntPtr pCPCMD, IntPtr& ppTarget, Boolean& pfNeedsRelease)
   at Microsoft.Office.Uc.SignInConfigurationClass.ForgetMe(String Uri)
   at Microsoft.Lync.Model.SignInConfiguration.ForgetMe(String uri)

Yeah, it seems Microsoft forget a COM component registration when we deploy Skype For Business 2016. Fortunately, here is the registry script to fix it :

Set SignInConfiguration Keys Script

Moreover, I have writter a powershell script to check pre requisites for Lync 2013 and Skype For Business 2016

Skype For Business Pre requisites checks script

In the next article on this subject, we will explore a bit the c# APIs.

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