Call flow for third-party pause (Q88)

The information in this article applies to:

Here is a prototypical call flow written from the point of view of the videoconferencing endpoint that receives an empty termCapSet.

Typical call is up and running with audio and video in both directions.

Remote endpoint initiates pause.

<-- TCS (empty: all OPTIONAL ASN.1 components are absent,
         leaving just seqNum and protocolIdentifier)

Knowledge of the remote endpoint's capabilities is completely removed, as if the endpoint never received them.

--> TCSAck
--> CLC audio
--> CLC video
<-- CLCAck audio
<-- CLCAck video

Endpoint is paused but still able to receive incoming audio and video. Remote endpoint could close, reopen, etc. its channels if it wanted to. It could even send another empty TCS.

Remote endpoint initiates "resume," or unpauses the endpoint.

<-- TCS (fully populated with possibly different caps than before)
--> TCSAck
--> MSD
<-- MSDAck
--> MSDAck
--> OLC audio
--> OLC video
<-- OLCAck audio
<-- OLCAck video

Call is now re-established with audio and video in both directions.