Engine & deployment

Settings

The engine and platform settings an operator is most likely to change.

These are environment variables, read once at start. This page lists the ones that shape call behaviour. The complete tables, generated from the code, ship with the backend in its deployment guide.

Choosing engines and modes (platform)

Variable	Default	Meaning
`DEFAULT_ENGINE`	`mock`	Engine for agents that do not choose one
`TELEPHONY_MODE`	`mock`	`mock` simulates numbers and dialling; `live` uses the provider
`OWN_AGENT_WS_URL`		Public WebSocket address of the voice engine
`ENGINE_PUBLIC_WS_URL`	`ws://127.0.0.1:9140/web`	Address the browser voice test connects to
`ENGINE_SHARED_SECRET`		Shared by the platform and the engine
`ENGINE_HEALTH_URL`		The engine's capacity endpoint, so readiness and admission can see it
`PUBLIC_BASE_URL`		The API's public address, used in provider callbacks
`ALLOW_PRIVATE_URLS`	`false`	Lets webhooks, tools and knowledge-base URLs reach private addresses. Development only.
`REQUIRE_VERIFIED_EMAIL`	`false`	Blocks calling until the login's email is confirmed

Models (engine)

Variable	Default	Meaning
`ASR_BACKEND`, `LLM_BACKEND`, `TTS_BACKEND`	`openai`	Backend per stage
`ASR_BASE_URL`, `LLM_BASE_URL`, `TTS_BASE_URL`		Endpoints of OpenAI-style servers
`ASR_MODEL`, `LLM_MODEL`, `TTS_MODEL`	`whisper-1`, `gpt-4o-mini`, `tts-1`	Model names sent to them
`LLM_USE_AGENT_MODEL`	`true`	`false` pins `LLM_MODEL` whatever the agent says
`LLM_TEMPERATURE`, `LLM_MAX_TOKENS`	`0.3`, `250`	Used when the agent sets none
`TTS_VOICE`		Default voice
`TTS_USE_AGENT_VOICE`, `TTS_VOICE_MAP`	`false`	Pass the agent's voice through, or map it
`ASR_MAX_CONCURRENCY`, `LLM_MAX_CONCURRENCY`, `TTS_MAX_CONCURRENCY`	`4`, `4`, `2`	Requests in flight across all calls

Turn-taking (engine)

Variable	Default	Effect
`VAD_END_SILENCE_SHORT_MS`, `VAD_END_SILENCE_MS`, `VAD_END_SILENCE_LONG_MS`	`450`, `600`, `800`	Silence that ends a turn. The largest part of response time. Lower answers sooner and cuts in on callers who pause.
`VAD_ADAPTIVE_END`	`true`	`false` always uses the middle value
`VAD_START_MS`	`100`	Speech needed to start an utterance
`BARGE_IN_MIN_SPEECH_MS`	`260`	Speech needed to pause the agent
`INTERRUPTION_WORDS`	`1`	Words needed to take the turn, when the agent sets none
`VAD_ENERGY_THRESHOLD`, `VAD_NOISE_RATIO`	`500`, `3`	Raise on noisy lines
`ECHO_GUARD`	`true`	The echo guard
`NOISE_SUPPRESSION`	`off`	`light` enables spectral suppression
`TURN_MERGE_GRACE_MS`	`2000`	Window in which a resumed sentence is merged into the previous turn

Call limits (engine)

Variable	Default	Meaning
`MAX_CALLS`	`8`	Simultaneous calls per engine process; 0 means no limit
`SHUTDOWN_GRACE_SECONDS`	`120`	Time calls in progress get to finish on shutdown
`HANGUP_AFTER_SILENCE`	`10`	Seconds of silence before hanging up, when the agent sets none
`CALL_TERMINATE`	`600`	Longest call in seconds, when the agent sets none
`MAX_CONSECUTIVE_FAILURES`	`3`	Model failures in a row before the call is ended
`WEB_MAX_SECONDS`	`300`	Longest browser test call
`TOOL_TIMEOUT`	`10`	Seconds a function tool may take

Features (engine)

Variable	Default	Meaning
`PII_REDACTION`	`mask`	`off`, `mask` or `strict`, when neither the agent nor the workspace sets a policy
`RECORD_CALLS`		Empty records the calls the platform knows about
`KB_TOP_K`, `KB_TIMEOUT`	`3`, `1.5`	Passages per search and the time allowed
`DTMF_COLLECT_TIMEOUT`, `DTMF_INTER_DIGIT_TIMEOUT`	`20`, `5`	Keypad entry, in seconds
`VOICEMAIL_WINDOW`	`12`	Seconds after answer in which voicemail is looked for
`WEB_ALLOWED_ORIGINS`	the local dashboard	Pages allowed to open a browser test call
`EXOTEL_WS_USER`, `EXOTEL_WS_PASSWORD`		Credentials Exotel must present. Unset refuses every Exotel connection.

Reliability (platform)

Variable	Meaning
`IDEMPOTENCY_TTL_HOURS`	How long idempotency keys are remembered
`JOB_MAX_TRIES`	Attempts before a background job goes to the dead-letter list
`RECORDING_RETENTION_DAYS`	When recordings are deleted. By default they are kept.
`MAX_BODY_BYTES`	Largest request body outside the upload routes
`DB_POOL_SIZE`, `DB_MAX_OVERFLOW`	Database connections per process

Billing, messaging and email (platform)

The price book file, tax settings, the payment provider, the SMS and WhatsApp providers and the email backend each have their own settings. See Billing and the deployment summary.