Lync Server 2010 Join Meeting Audio Scenarios

With Lync Server 2010, conferences provide the option to dial out to participants. The dial out to PSTN experience varies depending on whether the organizer and participant are enabled for Enterprise Voice. This article covers the possible scenarios in this user experience.

Author: Rui Maximo with Geoff Clark

Publication date: June 2011

Product version: Lync Server 2010

When participants join a Lync conference using the Join Meeting Audio, Call me at option, as shown in Figure 1, the A/V Conferencing Server dials the user’s PSTN phone number. This experience varies depending on whether the participant and the organizer are enabled for Enterprise Voice.

Figure 1. Call me at option


There are four possible scenarios:

1. Both the organizer and identified participant are enabled for Enterprise Voice.

2. Only the organizer is enabled for Enterprise Voice and the participant is either

a. Anonymous

b. Not enabled for Enterprise Voice

3. Only the participant is enabled for Enterprise Voice.

4. Neither the organizer nor the participant are enabled for Enterprise Voice.

Let’s examine these scenarios in more detail.

In scenarios 1 and 3, Lync Server uses the participant’s voice policy and dial plan normalization rules to dial the PSTN phone number. The call is routed to the Mediation Server, through the gateway to the PSTN. The user cannot be anonymous.

In scenarios 2.b and 4, Lync Server cannot dial the PSTN phone number, because the participant is not enabled for Enterprise Voice. Lync Server cannot find a voice policy associated with the user to enforce call routing. This behavior is expected and by design.

In scenario 2.a, where the user is anonymous, Lync Server dials the anonymous user using the organizer’s dial plan and voice policy.

Here’s an example:

Jim creates a Lync meeting and invites Michele, Patrick, and Ryan as participants.

Jim is not enabled for Enterprise Voice. Therefore, when Jim joins the meeting, his audio connects through his computer and is not routed as a voice call.

Michele is an anonymous user. When she attempts to join the meeting using the Call me at feature, the call fails, and she is unable to connect to the meeting’s audio. Michele must dial directly into the meeting.

Patrick is enabled for Enterprise Voice. When he tries to join the meeting using the Call me at feature, the call comes in, and he joins the audio portion of the meeting.

Ryan is not enabled for Enterprise Voice. When he uses the Call me at feature to connect to the meeting audio, his PSTN phone never rings. The PSTN call cannot be routed, because there’s no voice policy to enforce.

The only option for A/V Conferencing Server to dial PSTN phone numbers (using the Call me at feature) for non-enabled Enterprise Voice users (PC-to-phone) is to configure a static route on the Mediation Server to allow all outbound calls. However, this configuration is not recommended, because it allows any Lync client to make outbound calls to any phone number. The Mediation Server translation rules are not applied, because this call is routed through a static route and not through Enterprise Voice outbound routing rules.


The Lync Server Call me at option dials out to the participant to join the audio portion of a Lync meeting. This feature requires the participant to be enabled for Enterprise Voice. If the participant is a Lync user, but not enabled for Enterprise Voice, Lync Server cannot call the participant’s PSTN phone number. If the participant is an anonymous user, Lync Server uses the organizer’s dial plan and voice policy to call the anonymous user.

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Comments (8)
  1. says:

    What I (and colleagues) would like to know, why was Lync not designed such that it can act as a standalone PSTN conferencing solution without EV?

    Many of our customers have expressed interest in deploying Lync as a standalone conferencing solution including a large healthcare organization doing a full on POC between Lync and Cisco MeetingPlace.

  2. Wolverine says:

    What if the customer has RCC deployed?

  3. MAGutowski says:

    Both of the above comments are in-line with what we are trying to do.  We are going to deploy Lync as the IM/UC/Conferencing solution but plan to integrate via RCC with our Cisco system.

    I currently have a test Lync system integrated to our Cisco 7.1.5 system and forced all calls to go to the mediation server through a static route.  It does mean that Lync loses control of who and what numbers can be dialed, however, our Cisco system will perform certain restrictions blocking carribbean calls, 976 numbers, etc.  So far I don't know why you Microsoft is not recommending it for this particular reason, other than it totally breaks EV if you should decided to deploy that at some point in the future.

  4. Geoff Clark says:

    Yes you can use a Static Route to get this scenario to work.  But it boils down to a non-tested scenario.  Also in this scenario we now are handing off control to the PBX with a static route.  With that said we can't apply policies to the call and have to leave it up to the PBX to manage and manipulate the calls.

  5. Matt McGillen says:

    Hi – thanks for the post, it validates what I'm seeing in the field. However, if you look at the MS Lync licensing website:…/pricing-licensing.aspx

    You'll see that to "Automatically join meeting audio from PBX or other phone number" you just need the ECAL, not the plus CAL. And because this says "From PBX" I'm pretty sure it's not just talking about anonymous web-based users.

    My question then, is: if you only need the ECAL to join, why does it fail without a PlusCAL feature? Thanks! – Matt

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