Participant Model | AgentDuet SDK

Every Call has two parties and one agent. On outbound calls, inbound audio for the remote party is typically on the callee track - selecting the wrong stream is a common integration error.

Parties vs agent

Parties: caller (who placed the call) and callee (who was called).
One of them is always the subscriber (your connector’s line); the other is the external participant.
The agent is your code. It listens via caller / callee .audio_stream() and speaks with send_audio(). It is not a third party identity.

caller / callee are membership, not liveness - who the call is between, not who has picked up yet.

Inbound seeding

Field	Value
`caller`	External `participant`
`callee`	Your `subscriber`

Outbound

After make_call + dial, the dialed party is typically on the callee track - stream call.callee.audio_stream().

The one rule: is the agent in the audio path?

Shape	Calls	Meaning
Ambient	1	Parties talk directly. Agent listens / speaks to one side or both.
In-path	1 per party	Parties do not hear each other; agent relays (e.g. live translator).

Ambient modes (after `connect()`)

Mode	Who hears the agent
`spy()`	Nobody
`whisper()`	Subscriber only
`barge()`	Both parties

Subscriber on inbound = your staff line (callee). On outbound = your line (caller).

Worked examples

Scenario	Calls	Shape
Voice assistant answers for the subscriber	1	`answer()`; agent is the callee’s voice
Call monitor / coach	1	`connect()` then `spy` → `whisper` / `barge`
Live translator	2	One `Call` per human; agent in-path on both

Per-party audio

1 async for chunk in call.caller.audio_stream():
2     ...  # only the caller
3 
4 async for chunk in call.callee.audio_stream():
5     ...  # only the callee

Call Commands