Skype/Lync MobileApplicationExpiryTimeInDays

The Skype/Lync Mobile Client and Simultaneous Ring can create an interesting situation.  When you sign into a Skype Mobile Client you are prompted to enter in the phone number of the device, this is to prevent PSTN calls going to your cell phone via SimRing while your Skype Mobile Client is signed in.  When you sign out of the mobile client, then calls to your cell phone would resume because that “Endpoint” with the cell phone number is no longer a Skype registered endpoint.

Other possible issues may now include the server sending IM’s, Calls and screen shares to the no longer available endpoint, even though other endpoint clients are signed in for the user.  Eddie B, please let me know if the below changes end up resolving your issues.  Would be great if it did.

Each Skype Endpoint has a unique ID which can change possibly from performing a phone device reset, software updates, and definitely when transferring to a new phone device.  It might also occur when moving from an Internal AP to Cellular Data.  We were never able to pinpoint all the exact reasons for a Mobile device to register and a new Skype/Lync Client endpoint.  Whatever the root cause, if this happens while the Skype Mobile client is signed in, that “Endpoint” will not be removed from the system for 15 days.

Changing the default value from 15 to 1 day helps to keep this issue in check, and the endpoint expires out most often before a user realizes there might be an issue.

The reason for the posting and is that a reader on a previous post commented that this might resolve issues that they’re having with the Skype for Business Mac client.  Hopefully after he’ll have a chance to respond on if this was a positive change for his environment.

  1. Open up a Command Prompt as Admin
  2. Change to the Web Components\Ext directory, e.g.  C:\Program Files\Skype for Business Server 2015\Web Components\Ucwa\Ext
  3. run:  Notepad Web.config  This will open up the web.config file in notepad in a way that you can Save the changes.
  4. Change “MobileApplicationExpiryTimeInDays” from 15 to 1.
  5. File | Save, or close and Save Changes
  6. Repeat for the Int directory, C:\Program Files\Skype for Business Server 2015\Web Components\Ucwa\Int
  7. Restart the Server or perform an IISRESET.

I have not experimented with trying to use .5 days instead of 1 day to see if that is a valid entry, a setting of 1 has been sufficient for all my clients thus far.  This particular entry might also only accept integer values.

If you are applying this change to a pre CU-277 Skype system, you will need to redo these changes again after applying CU-277.  These two files get over written during this particular update and probably again for future ones going forward.  Do NOT restore a previous file version, there may be other changes, hence Document and verify after applying CU’s.  This just happen to be the first CU to over write my change in 4+ years of applying it, and now I expect I will be re-doing the change with ever future CU going forward.

4 thoughts on “Skype/Lync MobileApplicationExpiryTimeInDays”

  1. I would love to hear if this fixed the issue, because we have users reporting this also on MAC and Mobile clients, since both are based on UCWA, it makes sense.

    -Tim E. Brown

    1. We are still Lync 2013 Server, but were experiencing the same problems on Mobile and SfB for Mac clients. We implemented this fix last weekend and so far the reports are good. Users who were previously unable to sign in are now able to do so. I also checked accounts that I knew had “stale” connections using Pat Richard’s excellent get-csconnections script ( and the stale connections are removed.

  2. Hey Korbyn,

    I realize it’s been quite a while, but we were able to successfully implement this last May in our prod environment. It’s greatly diminished the amount of issues with stale sessions–works for both Mac and mobile clients. Thanks a lot for posting.

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