Hello,

I had developed a desktop application based on Lync SDK 2010. I was using Plan P1 plan for my application. It had worked great when I attend the meeting via Lync 2010 attendee. But when I attend the meeting via Lync Web App, the attendees were removed from the meetings. I was change Lync plan to Lync Online (Plan 2). Still I am getting the same issue. I got the below logs from browser. 

Dumping Logs: Dump Requested Time - Tue Sep 03 2013 11:10:59 GMT-0400 (Eastern Standard Time), Reference Time - Tue Sep 03 2013 11:10:42 GMT-0400 (Eastern Standard Time) 11:10:42:943, TL_INFO, , CoreUX, Logging Started!!!, Lync_Client_CoreUx_StartPage$start 11:10:43:79, TL_INFO, , Framework, Desired major ver=15.8; Desired minor ver=8641.0; Desired Mac minor ver=8546.500; Current ver=15.8@8641.0, Lync_Client_PluginFramework_PluginManager$$1T_1 11:10:43:92, TL_INFO, , Accessibility, Marking role RoleType as Abstract, Lync_Client_Accessibility_Taxanomy_Roles_RoleTaxanomyInformation$$2N 11:10:43:118, TL_INFO, , Accessibility, Marking role Structure as Abstract, Lync_Client_Accessibility_Taxanomy_Roles_RoleTaxanomyInformation$$2N 11:10:43:120, TL_INFO, , Accessibility, Marking role Section as Abstract, Lync_Client_Accessibility_Taxanomy_Roles_RoleTaxanomyInformation$$2N 11:10:43:131, TL_INFO, , Accessibility, Marking role Widget as Abstract, Lync_Client_Accessibility_Taxanomy_Roles_RoleTaxanomyInformation$$2N 11:10:43:133, TL_INFO, , Accessibility, Marking role Command as Abstract, Lync_Client_Accessibility_Taxanomy_Roles_RoleTaxanomyInformation$$2N 11:10:43:137, TL_INFO, , Accessibility, Marking role Input as Abstract, Lync_Client_Accessibility_Taxanomy_Roles_RoleTaxanomyInformation$$2N 11:10:43:140, TL_INFO, , Accessibility, Marking role Window as Abstract, Lync_Client_Accessibility_Taxanomy_Roles_RoleTaxanomyInformation$$2N 11:10:43:146, TL_INFO, , Accessibility, Marking role Composite as Abstract, Lync_Client_Accessibility_Taxanomy_Roles_RoleTaxanomyInformation$$2N 11:10:43:148, TL_INFO, , Accessibility, Marking role Select as Abstract, Lync_Client_Accessibility_Taxanomy_Roles_RoleTaxanomyInformation$$2N 11:10:43:173, TL_INFO, , Accessibility, Marking role SectionHead as Abstract, Lync_Client_Accessibility_Taxanomy_Roles_RoleTaxanomyInformation$$2N 11:10:43:181, TL_INFO, , CoreUX, Cannot set HC user options; will set later, Lync_Client_CoreUx_LwaShell$computeHighContrastMode 11:10:43:182, TL_INFO, , CoreUX, Build Information below, Lync_Client_CoreUx_StartPage$start 11:10:43:183, TL_INFO, , CoreUX, productVersion:5.0.8641.0, 11:10:43:183, TL_INFO, , CoreUX, buildType:fre, 11:10:43:184, TL_INFO, , CoreUX, branch:lcs_w16_r5, 11:10:43:185, TL_INFO, , CoreUX, buildArch:amd64, 11:10:43:185, TL_INFO, , CoreUX, productBuild:8641, 11:10:43:186, TL_INFO, , CoreUX, majorVersion:5,11:10:43:186, TL_INFO, , CoreUX, minorVersion:0, 11:10:43:187, TL_INFO, , CoreUX, productName:Microsoft Lync Web App, 11:10:43:188, TL_INFO, , CoreUX, productShortName:Lync Web App, 11:10:43:189, TL_INFO, , CoreUX, copyright:Copyright (c) Microsoft Corporation. All rights reserved., 11:10:43:189, TL_INFO, , CoreUX, copyrightYear:2012, 11:10:43:190, TL_INFO, , CoreUX, legalCopyright: Microsoft Corporation. All rights reserved., 11:10:43:190, TL_INFO, , CoreUX, legalCopyrightWithYear: 2012 Microsoft Corporation. All rights reserved., 11:10:43:191, TL_INFO, , CoreUX, companyName:Microsoft Corporation, 11:10:43:191, TL_INFO, , CoreUX, isExternal:true,11:10:43:192, TL_INFO, , CoreUX, currentLocale:en-us, 11:10:43:192, TL_INFO, , CoreUX, currentLCID:1033, 11:10:43:193, TL_INFO, , CoreUX, isRtl:false, 11:10:43:193, TL_INFO, , CoreUX, UserAgent : Mozilla/5.0 (Windows NT 6.2; WOW64; rv:23.0) Gecko/20100101 Firefox/23.0, Lync_Client_CoreUx_StartPage$start 11:10:44:339, TL_INFO, , CoreUX, ExitUIStart reason 3, Lync_Client_CoreUx_StartPage$exitUIStart 11:10:44:347, TL_INFO, , UICoreConversations, GetExitConversationReasonTextFromCode for 3, Lync_Client_Controls_Conversation_ExitMeetingFinalViewModel$$4F_3 Dumping Logs ENDED Logger Registered: Tue Sep 03 2013 11:10:59 GMT-0400 (Eastern Standard Time), Reference Time - Tue Sep 03 2013 11:10:42 GMT-0400 (Eastern Standard Time) 11:11:0:110, TL_INFO, , Accessibility, Resetting IsFocusSetFromPopup, Lync_Client_Accessibility_Navigation_TabBucket$$2L_0

Thanks for any help.

It looks like you are having trouble with the Lync Web App.  This forum is focused on development with the Lync client API, so it's unlikely to get a quick answer from this community. I will try to direct your post to the correct forum for Lync Web App on TechNet.

Some questions need to be clarified.

1. You use the custom desktop application to create a meeting, do you?
2. Another user use Lync 2010 attendee to join the meeting initiated by your custom desktop application successfully?
3. Other users cant join the meeting initiated by the custom desktop application via Lync Web app?

You should check if you can join the meeting via Lync Web App with the client provided by Microsoft with Plan P1 and Plan 2.

For the features provided by Plan P1 and Plan P2, you can get better response in Office 365 forum.

http://community.office365.com/en-us/forums/default.aspx

1. I am joining the conference via my application with already created meeting link.
2. When I click the meeting link, it goes to Lync Web App. The Lync Attendee 2010 could not trigger. But I am able to attend the meeting via Lync Client 2010 and Lync Client 2013.
3. Other user able to join the  meeting via lync web App, but they are disconnected within few minutes and the browser shows You were removed from the meeting message.