Provide an external WebRTC Offer and synchronously wait for an Answer to be generated. Optionally allows for the caller to specify an external
sessionId along with the Offer. This is the one and only call in the synchronous WebRTC connection establishment process.
Using this endpoint isn't recommended unless you provide your own
iceServerswith STUN, TURN and TURNS capabilities. If none or STUN only are provided, the call setup can fail in many network topologies.
The session_id generated for this call. Is the same value as in the Request Body if sent, otherwise an opaque string is generated. This value is required to invoke Renegotiate Live WebRTC or Stop Live WebRTC.