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Voice SDKs

Three client paths, all against the same REST API and media pipeline.

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TypeScript

Generated from the OpenAPI spec, or hand-rolled against the REST API. Configure a base URL and an auth header, and an outbound call is a handful of lines. The SDK guide covers:
  • Placing an outbound call, minimally
  • Outbound calls with idempotency and retries
  • Inbound webhook handlers for Express and Next.js App Router
Send an Idempotency-Key on POST /make-call. It gives you 24-hour replay protection, so a retry after a network timeout will not place a second real call.

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Python

The same surface for Python services, including webhook signature verification.

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Web SDK (browser calls)

POST /voice/web-calls mints a signed browser voice session — a WebSocket URL plus a start message.
Because a web call uses the same media protocol and pipeline as a phone call, it inherits the entire platform — agents, custom tools, transfers with no-answer recovery, evals, billing — with nothing extra to configure.
No phone number is involved, so a browser call needs no Twilio number provisioning. It is the fastest way to exercise an agent end to end while building.

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Verifying webhooks

All three SDK paths need the same verification: HMAC-SHA256 over the raw request body, compared in constant time. See Webhooks. The same helper also covers custom tool call invocations, which are signed identically.