Resetting default Lync Conference ID’s

NOTE: What is suggested in this post is not supported by Microsoft.  I am typically leery of posting these types of solutions but it fixes a specific problem.  Use at your own risk!

So over the past seven days I have been ask either directly by customers, through e-mail, on the Microsoft forums or other avenues of how to reset a users default conference ID automatically. Typically when this request is happening it’s part of a larger issue.  Maybe you changed default SIP domains and removed the old domain.  Maybe you lost your file share and don’t have a backup to restore conferencing.  Whatever the case is, there may come a time you need to reset everyone’s ID’s because you lost conferencing.  I always find people willing to take a little more risk when something is broken beyond repair.

There is no out of the box solution for this.  Users can visit the dial-in page and manually reset the ID’s.  This works if you have a small problem but if you have lots of people it will become tiresome of support calls walking people through the process.

So what other option do you have? Before we get there, let’s look at where conferences are stored in database.  In Lync 2013 that is in the front-end server RTCLocal.  For 2010, that is in the back-end database instance.  For the remainder of this conversation we are looking at Lync 2013.

Going to your Lync 2013 RTCLocal SQL instance you will find three databases.  The one we are interested in is the RTC database.  Inside of that are two tables that are helpful – Resource and Conference. The resource table contains every user who has logged into that server.  Be it internal, external, partners, etc.  I’m starting here because I want to limit my testing.

So the first thing I need to do is find my resource ID.

SELECT * FROM resource WHERE userAtHost = ‘’

Here we can see 293 is my resource ID.


So now if I got to the conference table I can get back all of the conferences that are assigned to me:


Here we can see I have one static (or default conference) and two that are not.  So when I create a new conference I automatically get assigned the conference ID of CDBJ2FMZ.

So when the Outlook client requests a meeting (assuming you are using the default conference ID for meetings), that request is sent to Lync which sends it up to the server.  The server than looks into this table.  If the user has a static (default) conference assigned to them, then it will return that ID to the user.  If there is no static (default) conference, the system will generate a new conference ID, mark it as static and return that to the user.

So if I manually change static from True to False.  We see generating a new meeting request the table changes like the following:

Changed static to false
Clicked new Lync Meeting in Outlook

My user has now been assigned a new static (default) conference because of this change.

So what is the end user experience for this?  The answer is it depends.  If the user has already requested a meeting the Outlook client will cache that information.  That is why the first time you request a new meeting each morning (assuming you close Outlook at night) it can take a few seconds but all other Lync meetings happen nearly instantly.  So here are the different scenarios I’ve tested:

Outlook Client Open (User has not yet requested a meeting today)
The outlook client will reach into the database, find there is no static ID and returns a new static ID to the user by generating a new record.

Outlook Client Open (User has requested a meeting today)
The outlook client will use the cached information and schedule the meeting using the old ID.

What happens when a person tries to join an existing (old) meeting?
Since you have not deleted the old conference, the system will behave like normal and allow you into the conference.  However, if you are doing this type of solution, most likely that old conference was broken and that is why you are doing this.

What happens if you modify the meeting with the old static ID in Outlook?
Outlook when opening the meeting will go and verify the state of the meeting.  Since Outlook believes it’s the “default” meeting it will prompt you that things have changed:

Message from Outlook Client

After clicking OK, the meeting will automatically update to the new static (default) conference and instruct the user to send an update to all participants.

Once you have tested this, you could make the change using a simple SQL Update Query.

Remember, this would never be considered the supported solution but occasionally you have to go outside the box to fix a very broken system.



13 thoughts on “Resetting default Lync Conference ID’s

  • October 14, 2013 at 5:29 am

    Nice work, was looking for a manual update myself but you beat me to it. Thanks!

  • October 20, 2013 at 6:29 pm

    Using this method, can you manually set the conference ID? My company’s prior conferencing system used the extension number which was a well liked feature (versus the generated number approach in lync).

    • October 21, 2013 at 2:00 pm

      You could certainly try it. In theory, it would work, but keep in mind that manually editing this table is not supported by Microsoft and you are on your own for anything you might break.

  • March 17, 2014 at 8:02 pm

    Although it looks like this might work, I’d advise caution.

    Lync maintains a master version of this data on the primary host in your routing group, but it also maintains replicas on the 2 backup hosts. Making a change on just the primary will probably work, but i don’t think LyncFabric will just replicate out the change to the two other hosts in your routing group automagically.

    I’m not sure Lync has the logic to just check for these changes… If it does not update on the other two hosts, then you could end up in a invalid situation where you have old static rooms floating around on other hosts in your pool that were never cleared up.

    That’d be bad if you end up being primary on one of those hosts again, i’m not sure it could write the additional static room entry into the db.

    I suppose you could write the change into the other two FE DBs, but again – not sure what the consequences of that would be.

    • March 18, 2014 at 1:51 am

      Absolutely should use lots of caution. As mentioned, this is not supported and only should be used in extreme situations. As for the other front-ends, all testing was done on standard edition. In the event of an Enterprise Pool deployment, you can do the following:

      – Change it on the primary routing group front-end
      – Move user to a another pool. This will update move the primary information and than delete from all three front-ends
      – Move user back. It’s now updated.

      Again, this would never be supported and only used in that dire emergency.

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  • February 4, 2015 at 9:59 pm

    This process worked well for me. Thanks for posting! Peace.

  • June 9, 2015 at 5:47 am

    I am not familiar with SQl and try to avoid changing any table. I had the issue when pstn users calls lync conf ID and after they entered conference ID to get a message a “cannot find a conference id with that number”. They went to conf dial in page and changed the conf id , update the meeting in outlooks and send updates. Everything worked fine for a while , but I am hearing that some people having the issues again. We have 2 front 2013 Lync servers and I am concern that maybe update does not replicate to both servers. How can I check that users data are the same on both front servers. Also can somebody explain me what information about conferences are kept on front end servers, the file share and back end.

  • November 28, 2015 at 1:28 am

    Using Dial in page by the users themselves, will do similar fix and you won’t have to go through all these agony. At the same time, Thanks for Richard.

    • December 12, 2015 at 3:03 am

      Agreed. This had more to do with “figuring out” how this worked and not forcing users to do this. Small company, easy to get everyone to do it, large enterprise, a bit harder.

  • March 2, 2016 at 8:55 pm

    Thanks for this! Looks like it is still valid on Skype for Business 2015.
    One question – I’m in an Enterprise pool and it looks like the OrganizerID and ConfID is different on all three of my FE servers; is this a replication issue?

  • October 18, 2016 at 8:30 am

    Is there a way to do this for the whole organization?

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