Voice Platform APIKeypad (DTMF)

Send DTMF sequence

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**Rate limit: Per command** · **Burst:** 20 · **Refill:** 20 req/s Send ordered DTMF keys and waits to the remote party on an answered phone session. Each action controls its own key duration or delay. Only one sequence can be active per session. Ringing calls and standalone WebSocket sessions created with `POST /v1/sessions:connectWebsocket` are not supported. `wait.duration_ms` is a minimum delay before the next action; dispatch may occur later. Action order is preserved. The acceptance webhook omits the sequence to protect secrets and confirms acceptance only, not remote handling. **Triggered webhook:** `command.dtmf.send.accepted`

Authentication

AuthorizationBearer
Application auth. Send `Authorization: Bearer <app_uuid>:<api_key>`. See [Authentication](https://voice-platform.docs.buildwithfern.com/api/authentication) for details.

Path parameters

uuidstringRequired

Session UUID (format {5-char-prefix}-{uuid}).

Headers

Idempotency-KeystringOptionalformat: "^[a-zA-Z0-9._-]+$"<=128 characters
Optional client-generated key for a mutating endpoint. It identifies one method, route, query, content type, and exact raw body within the authenticated app. Reusing it for a different request returns 422. While its record exists, a retry replays the original accepted response when available. Keys are valid for 1 hour. Allowed characters: letters, digits, dot, hyphen, underscore; max 128 characters. See the Idempotency guide.

Request

This endpoint expects an object.
sequencelist of objectsRequired
Ordered key and wait actions. Waits may appear anywhere and consecutive waits are allowed. The total nominal duration may not exceed ten minutes, and the sequence must include at least one key action.
operation_uuidstringOptionalformat: "uuid"
Optional caller-supplied per-command correlation id, a bare lowercase RFC-4122 v4 UUID (no prefix). Echoed back as `operation_uuid` in the 202 ack. A later lifecycle webhook carries it only when the gateway can unambiguously associate that event with this command; the field is correlation, not proof of causation. When omitted, the gateway mints one. Not an idempotency key — request deduplication is the `Idempotency-Key` header. Invalid input (not a v4 UUID) is rejected with `400 invalid_request`.

Response

Command accepted for async execution
operation_uuidstringformat: "uuid"
statusenum
already_endedtrueOptional

Optional. Set to true on idempotent terminal commands when the session was already in a terminal state at the time the request was received. Absent otherwise.

Errors

400
Bad Request Error
401
Unauthorized Error
404
Not Found Error
409
Conflict Error
413
Content Too Large Error
415
Unsupported Media Type Error
422
Unprocessable Entity Error
429
Too Many Requests Error
500
Internal Server Error
503
Service Unavailable Error