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Lync 2013 PSTN Conferencing with DTMF

Easier remote access with dial-in conferencing

Lync Server 2013 dial-in conferencing has come a long way since previous versions of the product, which date back to Office Communications Server 2007 R2 (OCS 2007 R2). One of the features of conferencing allows remote users to dial in into a conference from a public switched telephone network (PSTN) device or a Local Area Network (LAN) line, hence the name "dial-in conferencing." This solution is perfect when remote users don't have the ability to connect to a Lync online meeting with a Lync-capable device.

Now, what happens when the meeting organizer wants to launch and control the meeting but is on the road? Are the same meeting options available as the organizer would have when in the office? Can the organizer mute the audience or find out who is present in the meeting? I will take a closer look into the options a conference organizer has to control meetings when they are calling in remotely from a non-Lync device.

What is Lync 2013 Dial-In Conferencing?

The ability to host conferences "on-premises" instead of with a third-party provider was introduced in OCS 2007 and remains in Lync Server 2013. One of the options when deploying Lync Server 2013 enables PSTN dial-in conferencing. Now keep in mind, deploying dial-in conferencing requires the Lync 2013 Mediation Server to demystify the Mediation Server role in Lync Server 2013. Lync 2013 Mediation Server then acts as a media termination point for the incoming call for users to call into the meeting. Lync Server 2013 enables users to dial in to a conference over the telephone when the user is not able to connect via their Lync client. Many organizations have immediately realized the return on investment (ROI) when deploying dial-in conferencing over using third-party audio conferencing providers.

Dual-Tone Multi-Frequency (DTMF) Commands

During the creation of a scheduled Lync 2013 online meeting, the meeting organizer can choose to control how the meeting is set up by restricting access to the meeting or by making the meeting closed or restricted. In this case, dial-in users are requested to authenticate. If dial-in users fail or choose not to authenticate, they are transferred to the lobby where they wait until a leader accepts or rejects them, or they time out and are disconnected. After they are admitted to a conference, dial-in users can participate in the audio portion of the conference and can exercise dual-tone multi-frequency (DTMF) commands by using the phone keypad.

This is where the rubber meets the road; dial-in leaders can use several DTMF commands to control the meeting just as if they were in front of the rich Lync 2013 client. Several of the options include the ability to turn participants' mute on or off, lock or unlock the conference, admit people from the lobby, and turn entry and exit announcements on or off. Leaders can also use a DTMF command to admit everyone from the lobby, which changes the permissions of the meeting to allow anyone who subsequently joins. All dial-in participants can exercise DTMF commands to hear Help, listen to the conference roster, and mute themselves.

DTMF commands are set up out of the box for your Lync 2013 deployment. The basic commands can be gathered two different ways; the first method is to type in the following cmdlet in the Lync Management Shell:


You can see the results in Figure 1.

Figure 1: Dial-In Conferencing DTMF Configuration
Figure 1: Dial-In Conferencing DTMF Configuration

The second method can be accomplished by an authenticated Lync user. The user can click on the "Forgot your dial-in PIN?" URL on the Online Conferencing Page as Figure 2 shows.

Figure 2: Lync Online meeting page
Figure 2: Lync Online meeting page

The results of the URL for the DTMF conferencing controls will be displayed to the user as seen in Figure 3.

Figure 3: Dial-In Conferencing DTMF Commands from Dial-in Web Page
Figure 3: Dial-In Conferencing DTMF Commands from Dial-in Web Page

Editing the DTMF controls is as simple as adding the correct syntax to the cmdlet:


The following cmdlets can be used to specify different options for the DTMF controls:

Set-CsDialinConferencingDtmfConfiguration [-Identity ]
[-AdmitAll ]
[-AudienceMuteCommand ]
[-CommandCharacter <* (default) | #>]
[-EnableDisableAnnouncementsCommand ]
[-HelpCommand ]
[-LockUnlockConferenceCommand ]
[-MuteUnmuteCommand ]
[-PrivateRollCallCommand ]

Changing from the default options is as simple as associating the function with a different numerical number. The following cmdlet shows where two DTMF options are switched to numbers different from the default configurations.

Set-CsDialinConferencingDtmfConfiguration -EnableDisableAnnouncementsCommand 4 -AudienceMuteCommand 9

DTMF Flexibility

The flexibility for meeting organizers to control meetings even without being on a Lync client is here. Users will no longer have to connect on a Lync-enabled device to control aspects of the meeting. As the Lync administrator, these controls are simple to configure, and limiting the quantity of controls is possible, as well. Getting users accustomed to the DTMF commands will increase their knowledge of conferencing and PSTN, which will show conference organizers that it is easy to create a rich Lync meeting experience even when away from the office.

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