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Controlling media capability

Calls consist of three types of media - audio, video, and presentation - each in their own stream. Pexip Infinity allows you to control which types of media can be used for certain calls. This feature allows better resource management and smaller SDPs when calling out to known audio-only devices.

Limiting media capability

You can restrict the media capability either on a per-call basis (the call capability) or a per-conference basis (the conference capability), as follows:

Adding a participant to a conference

When dialing out to a participant from within a conference, either manually or automatically, you can choose whether the call will be audio-only, main video only, or main video plus presentation. In such cases, the called participant will not be able to escalate the call (for example, from an audio-only call to video).

Conference-wide limitations

You can apply limits to individual Virtual Meeting Rooms or Virtual Auditoriums, restricting them to be audio-only, main video only, or main video plus presentation. In such cases, participants calling in to the conference with a higher media capability will have their media limited. For example, when a participant dials in over video to an audio-only VMR, their call will be placed as audio-only and they will not subsequently be able to escalate the call.

Virtual Receptions

You can limit the conference capability of a Virtual Reception. Any restrictions will be applied to a call while it is accessing the Virtual Reception service. When the call is placed to the destination Virtual Meeting Room or Virtual Auditorium, the capability of that service will be applied instead. For example, if you limit your Virtual Reception to audio-only, when Alice calls it she will not receive any video and will only hear the audio prompts. However, when her call is then placed to the destination VMR which has a capability of main video, she will then be able to send and receive video as well as audio.

Note that SIP calls placed via a Virtual Reception with a capability limit will not be able to escalate beyond that capability, even when they are transferred to their final destination. So if Bob uses his SIP endpoint to make the same call as Alice, he too will only be able to hear the audio prompts while accessing the Virtual Reception, but he will not be able to send or receive video when he reaches the destination VMR.

Point-to point calls

For point-to-point calls made using the Distributed Gateway, you can limit media in two ways.

  • You can limit the media capability of the outbound call to audio-only, main video only, or main video plus presentation. For example, if the media capability is set to audio-only and Alice makes a video call to Bob, Bob will not be able to answer with video.
  • You can match the capability of the outbound call to that of the inbound call by using the Derived from inbound call type option. This means that if, for example, Alice makes an audio-only call to Bob, Bob will not be able to answer with video.

    Note that, when using Derived from inbound call type:

    • an audio-only call cannot later be escalated to video
    • auto-escalation of Lync calls (if enabled) will not work

Automatically escalating Lync / Skype for Business audio calls

You can control how Pexip Infinity handles incoming audio-only calls from Lync / Skype for Business* clients.

By default, Pexip Infinity treats the call as audio-only and does not send video back to the Lync participant.

This behavior can be changed on a platform-wide basis by selecting the Enable Lync auto-escalation setting on the Platform settings > Global configuration page.

When Lync auto-escalation is enabled, Pexip Infinity automatically escalates a Lync audio-only call so that it receives video from a conference (the Lync participant still only sends audio).

The following table shows the differences in conference experience based on the auto-escalation setting when a Lync client makes an audio call to a Pexip conference:

  Lync auto-escalation configuration
  Disabled (default) Enabled
The Lync participant... sees the conference avatar image ( by default) receives a video stream from the conference
Other conference participants see the Lync participant as... an audio-only participant indicator on the left side of the video window ( by default) a "no incoming video" indicator when the participant is shown as the main speaker or as a thumbnail ( by default)

In all cases, the Lync participant can still subsequently escalate to send (and receive) video.

* Note that where this documentation refers to "Lync", it represents both Microsoft Lync and Skype for Business unless explicitly stated otherwise.