Lync and Skype for Business Desktop Client Versions (MSI/C2R)

We receive a few number of questions related to the different versions of Skype for Business clients that are available.

If you already use Office 365 then probably you have the Skype for Business  2016 C2R (Click-to-Run).

Skype for Business 2016 C2R (Click-to-Run)

This is the version that is available in Office 365 and it contains the latest features, moving forward this version is also recommended for OnPrem (Lync Server 2013 and Skype for Business Server 2015).

How to check version:

Options > Help > About Skype for Business:

To check the Channel we need to go to another Office application, then File > Office Account:

Update List

Version and build numbers of update channel releases for Office 365 clients

Basic Version

How to install the Skype for Business Basic stand-alone client

Skype for Business 2016 MSI

This version is the Volume License version and doesn’t include all the features available in SfB 2016 C2R.

Both versions are supported but it’s recommended to use the SfB 2016 C2R version instead.

How to check the version

Please note that the version displayed in the Help > About is the MSO version and not the SfB Version.

To check the installed update we can use the following PowerShell cmdlet:

Get-ItemProperty “HKLM:\Software\Microsoft\Windows\CurrentVersion\App Paths\Lync.exe” | ForEach-Object {Get-ChildItem -Path $_.Path -Recurse lync.exe | Select-Object -ExpandProperty VersionInfo | Select FileDescription,ProductVersion}

Alternatively, go to the Tracing Folder and check the ETL filename:


Update List

Skype for Business 2016 Client Update List

Basic Version

Microsoft Skype for Business Basic (32/64 Bit)

Please note that SfB Basic version doesn’t include the same features as the SfB2016 MSI client, however, we can use the same updates.

Lync 2013/Skype for Business 2015 C2R (Click-to-Run)

This version was available for Office 365 and it contains the same features as the Lync 2013/Skype for Business 2015 MSI

How to check the version

Options > Help > About Skype for Business

We can also check on another Office application, then File > Office Account:

Update List

Update history for Office 2013

Lync 2013/Skype for Business 2015 MSI

This version started as Lync 2013 and it was renamed to Skype for Business 2015 on April 14, 2015. This version has the same features as Lync2013/SfB2015 Click-to-Run.

How to check the version

Options > Help > About Skype for Business

Update List

Lync 2013/Skype for Business 2015 Client Update List

Basic Version

Microsoft Lync Basic 2013 (32 Bit)

Microsoft Lync Basic 2013 (64 Bit)

Please note that these versions doesn’t include the same features as the Lync2013/SfB2015 MSI client, however, we can use the same updates.

Desktop client feature comparison for Skype for Business Server 2015

Lync/SfB Client: Disable file upload to external conferences

In the March 2018 update for Lync2013/SfB2015 and SfB2016 a new setting was included that can disable file upload to external conferences (Federated and Anonymous).

Before this update the Lync/SfB Client didn’t had a setting that could prevent file upload to external meetings:

We can configure the EnableExternalFileTransferInConference setting with Inband Policy or Register Key:

Inband Policy

$a = New-CsClientPolicyEntry –Name “EnableExternalFileTransferInConference” –Value $false
Set-CsClientPolicy –Identity <Policy Name> –PolicyEntry @{Add=$a}

Command Prompt

Lync 2013/Skype for Business 2015
reg add HKLM\Software\Policies\Microsoft\Office\15.0\Lync /v EnableExternalFileTransferInConference /t REG_DWORD /d 0 /f

Skype for Business 2016
reg add HKLM\Software\Policies\Microsoft\Office\16.0\Lync /v EnableExternalFileTransferInConference /t REG_DWORD /d 0 /f


Lync 2013/Skype for Business 2015
New-Item -Path “HKLM:Software\Policies\Microsoft\Office\15.0\Lync” -Force
New-ItemProperty -Path “HKLM:Software\Policies\Microsoft\Office\15.0\Lync” -Name EnableExternalFileTransferInConference -Type DWORD -Value 0 -Force

Skype for Business 2016
New-Item -Path “HKLM:Software\Policies\Microsoft\Office\16.0\Lync” -Force
New-ItemProperty -Path “HKLM:Software\Policies\Microsoft\Office\16.0\Lync” -Name EnableExternalFileTransferInConference -Type DWORD -Value 0 -Force

Please note that this registry key is available on a User Level (HKCU) and Local Machine (HKLM).

After disabling the upload the users won’t be able to upload file to External Conferences:

Please note that EnableExternalFileTransferInConference won’t block users to download files from external conferences:

The EnableExternalFileTransferInConference setting is available in the following Lync/SfB Client versions:

Office 365 ProPlus/Office Professional Plus 2016 Click-to-Run (after 16.0.8827.2082)

March 6, 2018, update for Skype for Business 2015 (Lync 2013) (KB4018290) (15.0.5015.1000)

March 6, 2018, update for Skype for Business 2016 (KB4011725) (16.0.4666.1000)

Enable Lync 2010 Meeting Invite Template in Lync2013/SfB2015

The January 2017 client update for Lync 2013/SfB2015 includes a new registry key that allows Lync2013/SfB2015 Meeting Addin to create a meeting invite similar to the one in Lync 2010 client.

For reference we need to look how Dial in Conferencing Numbers are configured:


Now, before any change, we can see that a meeting invite for a user from the UK region will look like this:

After applying the January 2017 update KB3141468 for Lync2013/SfB2015 Client we can use the registry key EnableW14MeetingInvitationTemplate to have the template as Lync 2010 Meeting Add-in. We can simply add the registry key with Command Prompt or PowerShell:

Command Prompt:
reg add HKCU\Software\Microsoft\Office\15.0\Lync\AddinPreference /v EnableW14MeetingInvitationTemplate /t REG_DWORD /d 1 /f

Set-ItemProperty -Path ‘HKCU:\Software\Microsoft\Office\15.0\Lync\AddinPreference’ -Name ‘EnableW14MeetingInvitationTemplate’ -Value ‘1’ -Type DWord

Note: This registry key is only available on a User Level, we cannot add it under HKEY_Local_Machine.

Now we can create a meeting in Outlook and the invite will be similar to Lync 2010 Addin:

Please note that this registry key setting is only available for the Lync2013/SfB2015 (15.0.4893.1000 or later). The update list is available here:

Lync 2013/Skype for Business 2015 Client Update List

Lync/SfB: User Presence won’t update to DND if the Secondary Monitor is shared

In a recent request we were asked why sharing the Second Monitor wasn’t updating the user presence to Do Not Disturb.

The Show me as DND when I share my desktop setting enable/disable the Lync/SfB Client to update the user presence when sharing:

However, even with this setting enabled the user presence will only be updated to Do Not Disturb if the Primary Monitor is shared:

Or if we share All Monitors:

The Show me as DND when I share my desktop setting was designed to prevent Lync/SfB IM and Call notifications to be displayed while we share the Primary Monitor.
Since these notifications aren’t shown in the Secondary Monitor we don’t need to update the user status to Do Not Disturb.

Enabling Lync/SfB Client to use proxy server for SIP traffic instead of trying direct connection

Update 2017/09/12 – Added SfB2016 MSI (16.0.4588.1001).

We had some reports that when trying to sign in to Skype for Business Online users were experiencing delays during the sign in process.

This behavior was related to environments were the Lync/SfB client is configured to use a Proxy Server to connect to the Skype for Business Online servers.

After researching the delay was occurring because the client was trying establish a direct connection and only after that connection timed out it would try to connect using the configured Proxy Server:

As a workaround we could configure the Firewalls to send RESET Packets and the Lync/SfB client won’t wait for the connection attempt to timeout.

Since the following client updates we can use a registry key to force the client to use proxy for all connections:

December 6, 2016, update for Skype for Business 2015 (Lync 2013) (KB3127976) (15.0.4885.1000)

Description of the security update for Skype for Business 2016: September 12, 2017 (16.0.4588.1001)

Office 365 ProPlus/Office Professional Plus 2016 Click-to-Run

Version 1611 (Build 7571.2072) – December 6, 2016

To configure Lync/SfB client to use a proxy server for SIP Traffic without attempting a direct connection we need to add the following registry key:

reg add HKCU\Software\Microsoft\UCCPlatform\Lync /v EnableDetectProxyForAllConnections /t REG_DWORD /d 1 /f

Note: This registry key is only available on a User Level, we cannot add it under HKEY_Local_Machine.

Lync 2013/Skype for Business 2015 Client Update List: September 2018

Here is the list for the Lync 2013/Skype for Business 2015 client updates:

Version Release Date KB Article Download
15.0.5067.1000 September 4, 2018 KB4092457 32 bit 64 bit
15.0.5059.1000 August 7, 2018 KB4032250 32 bit 64 bit
15.0.5049.1000 July 10, 2018 KB4022225 32 bit 64 bit
15.0.5041.1000 June 5, 2018 KB4022170 32 bit 64 bit
15.0.5031.1000 May 1, 2018 KB4018377 32 bit 64 bit
15.0.5023.1000 April 3, 2018 KB4018334 32 bit 64 bit
15.0.5015.1000 March 6, 2018 KB4018290 32 bit 64 bit
15.0.5007.1000 February 6, 2018 KB4011678 32 bit 64 bit
15.0.4997.1000 January 2, 2018 KB4011638 32 bit 64 bit
15.0.4989.1000 December 5, 2017 KB4011284 32 bit 64 bit
15.0.4981.1000 November 7, 2017 KB4011255 32 bit 64 bit
15.0.4971.1000 October 10, 2017 KB4011179 32 bit 64 bit
15.0.4963.1000 September 12, 2017 KB4011107 32 bit 64 bit
15.0.4953.1000 August 1, 2017 KB4011046 32 bit 64 bit
15.0.4945.1000 July 5, 2017 KB3213574 32 bit 64 bit
15.0.4933.1000 June 13, 2017 KB3191939 32 bit 64 bit
15.0.4927.1000 May 2, 2017 KB3191876 32 bit 64 bit
15.0.4919.1000 April 4, 2017 KB3178731 32 bit 64 bit
15.0.4911.1000 March 14, 2017 KB3172539 32 bit 64 bit
15.0.4903.1001 February 7, 2017 KB3161988 32 bit 64 bit
15.0.4893.1000 January 3, 2017 KB3141468 32 bit 64 bit
15.0.4885.1000 December 6, 2016 KB3127976 32 bit 64 bit
15.0.4875.1001 November 1, 2016 KB3127934 32 bit 64 bit
15.0.4867.1000 October 11, 2016 KB3118348 32 bit 64 bit
15.0.4859.1002 September 6, 2016 KB3118281 32 bit 64 bit
15.0.4849.1001 August 9, 2016 KB3115268 32 bit 64 bit
15.0.4841.1000 July 5, 2016 KB3115261 32 bit 64 bit
15.0.4833.1001 June 7, 2016 KB3115033 32 bit 64 bit
15.0.4815.1000 April 12, 2016 KB3114944 32 bit 64 bit
15.0.4805.1000 March 8, 2016 KB3114831 32 bit 64 bit
15.0.4797.1000 February 9, 2016 KB3114732 32 bit 64 bit
15.0.4787.1002 January 12, 2016 KB3114502 32 bit 64 bit
15.0.4779.1001 December 8, 2015 KB3114351 32 bit 64 bit
15.0.4771.1001 November 10, 2015 KB3101496 32 bit 64 bit
15.0.4763.1001 October 13, 2015 KB3085581 32 bit 64 bit
15.0.4753.1000 September 8, 2015 KB3085500 32 bit 64 bit
15.0.4745.1000 August 11, 2015 KB3055014 32 bit 64 bit
15.0.4737.1001 July 14, 2015 KB3054946 32 bit 64 bit
15.0.4727.1001 June 9, 2015 KB3054791 32 bit 64 bit
15.0.4719.1001 May 12, 2015 KB3039779 32 bit 64 bit
15.0.4711.1002 April 14, 2015 (1) KB2889923 32 bit 64 bit
15.0.4701.1000 March 10, 2015 KB2956174 32 bit 64 bit
15.0.4693.1001 February 10, 2015 KB2920744 32 bit 64 bit
15.0.4675.1000 December 9, 2014 KB2910927 32 bit 64 bit
15.0.4667.1001 November 11, 2014 KB2899507 32 bit 64 bit
15.0.4659.1001 October 2014 KB2889929 32 bit 64 bit
15.0.4649.1000 September 2014 KB2889860 32 bit 64 bit
15.0.4641.1001 August, 2014 KB2881070 32 bit 64 bit
15.0.4623.1000 June, 2014 KB2850074 32 bit 64 bit
15.0.4615.1001 May, 2014 KB2880980 32 bit 64 bit
15.0.4605.1003 April, 2014 KB2880474 32 bit 64 bit
15.0.4569.1508 March, 2014 KB2863908 32 bit 64 bit
15.0.4569.1503 February, 2014 (SP1) KB2817430 32 bit 64 bit
15.0.4551.1005 November 7, 2013 KB2825630 32 bit 64 bit
15.0.4517.1508 August 2013 KB2817621 32 bit 64 bit
15.0.4505.1510 July 9, 2013 KB2817465 32 bit 64 bit
15.0.4481.1004 May, 2013 KB2768004 32 bit 64 bit
15.0.4454.1509 February, 2013 KB2760512 32 bit 64 bit
15.0.4420.1017 RTM NA NA NA

(1) This update introduces the Skype for Business 2015 User Interface.

Please note that the download links listed are for the Lync 2013/Skype for Business 2015 update file, we should always check the necessary prerequisites in the related KB article.

As mentioned in a previous post Lync 2013/SfB 2015 client shares the same build as Lync 2013 VDI Plugin, this means that to update the  client from RTM we need to follow the same steps described in:

How to update the Lync VDI 2013 Plugin

To check the version we need to go to Options > Help > About Microsoft Lync/SfB:

Lync 2013 UI



Skype for Business 2015 UI



Lync/SfB Client tries to use proxy server instead of direct connection when using Proxy PAC on Windows 7

Update 2016/08/16 – This only happens on Windows 7, for Windows 8.1 and Windows 10 we don’t need to change the Proxy PAC file.

Recently we received some reports saying that Lync 2013 and Skype for Business 2015/2016 clients were trying to use a Proxy Server for lyncdiscover and lyncdiscoverinternal URLs when the Proxy was configured using a Proxy PAC script.

During the discovery process, the Lync/SfB client will check the Proxy PAC file with the following URLs:



For reference, here is a copy of my Proxy PAC file:

function FindProxyForURL(url, host) {

 /* Proxy all other hosts in gears.lab domain */
 if ((shExpMatch(host, "*.gears.lab"))) { return "DIRECT";}

 else { return "PROXY proxy.comm.lab:8080";}


We would expect that the following condition would cover the discovery URLs:

shExpMatch(host, “*.gears.lab”)

But it doesn’t, because the host variable will be:


Although the previous URL is valid it will cause issues in Windows 7.

We currently have two known workarounds:

1) Using the URL

This will match all the discovery URLs:

if ((shExpMatch(url, “http*://lyncdiscover*.gears.lab*”))) { return “DIRECT”;}

2) Using URL and Substring

This workaround requires that you check the length of each URL, but still it is also a valid alternative:

if (url.substring(0,29) == “http://lyncdiscover.gears.lab&#8221;) {return “DIRECT”;}
if (url.substring(0,30) == “https://lyncdiscover.gears.lab&#8221;) {return “DIRECT”;}
if (url.substring(0,37) == “http://lyncdiscoverinternal.gears.lab&#8221;) {return “DIRECT”;}
if (url.substring(0,38) == “https://lyncdiscoverinternal.gears.lab&#8221;) {return “DIRECT”;}