I've been struggling with getting an application endpoint working on UCMA 3.0. I am trying to run an application on a server separate from the Lync server which uses a registered ApplicationEndpoint to monitor presence and act as a bot which can send other users messages. I used to have my code working with a UserEndpoint (which was fine for monitoring presence), but did not have the capabilities to send IMs to other Lync users. After searching the web, I'm finally at the point where I'm getting this error when running my code: System.ArgumentException was unhandled Message=An ApplicationEndpoint can be registered only if proxy and Multual Tls have been specified. Source=Microsoft.Rtc.Collaboration StackTrace: at Microsoft.Rtc.Collaboration.ApplicationEndpoint..ctor(CollaborationPlatform platform, ApplicationEndpointSettings settings) at Waldo.endpointHelper.CreateApplicationEndpoint(ApplicationEndpointSettings applicationEndpointSettings) in C:\Users\l1m5\Desktop\waldoproject\trunk\WaldoSoln\waldoGrabPresence\endpointHelper.cs:line 117 at Waldo.endpointHelper.CreateEstablishedApplicationEndpoint(String endpointFriendlyName) in C:\Users\l1m5\Desktop\waldoproject\trunk\WaldoSoln\waldoGrabPresence\endpointHelper.cs:line 228 at Waldo.waldoGrabPresence.Run() in C:\Users\l1m5\Desktop\waldoproject\trunk\WaldoSoln\waldoGrabPresence\waldoGrabPresence.cs:line 60 at Waldo.waldoGrabPresence.Main(String[] args) in C:\Users\l1m5\Desktop\waldoproject\trunk\WaldoSoln\waldoGrabPresence\waldoGrabPresence.cs:line 42 at System.AppDomain._nExecuteAssembly(Assembly assembly, String[] args) at System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args) at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly() at System.Threading.ThreadHelper.ThreadStart_Context(Object state) at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state) at System.Threading.ThreadHelper.ThreadStart() InnerException: After some searching, I followed the instructions here: http://blogs.claritycon.com/blogs/michael_greenlee/archive/2009/03/21/installing-a-certificate-for-ucma-v2-0-applications.aspx to import a certificate onto the server that I'm trying to run the application on, but to no avail. So at this point, I think that there must be something wrong with how I'm setting up the ApplicationEndpointSettings, CollaberationPlatform or ApplicationEndpoint objects. Here's how I'm doing it: ApplicationEndpointSettings settings = new ApplicationEndpointSettings(_ownerURIPrompt, _serverFQDNPrompt, _trustedPortPrompt); ServerPlatformSettings settings = new ServerPlatformSettings(null, _serverFQDNPrompt, _trustedPortPrompt, _trustedApplicationGRUU); _collabPlatform = new CollaborationPlatform(settings); _applicationEndpoint = new ApplicationEndpoint(_collabPlatform, applicationEndpointSettings); Does anyone see any problems with what I'm doing? Or, better yet, does anyone know of a blog that walks you through establishing an application endpoint in the situation I'm in? I work really well with tutorials or samples, but have not found one that seems to accomplish what I'm trying to do. Thanks for the help!