The Five Rules of Ultravox
The Start Call 2-Step
The Five Rules of Ultravox
The Start Call 2-Step
Key concepts to understand before building a voice AI agent.
The fifth rule of building with Ultravox: “The Start Call 2-Step”.
Calls are the core of Ultravox. A call is an interaction between an agent and an end user.
Calls have two distinct steps:
Call Creation → Calls are configured and created using the Ultravox REST API’s /calls endpoint. Creating a call returns a joinUrl which is then used to join the call.
Join Call → Once created, calls are joined (and ended) using our client SDK, bridged to from a telephony provider, or connected from your server via WebSockets.