call_connected | Dial — Communication Stack for AI Agents

Direction: Dial → your server. Sent once per connection, immediately after the socket opens, before any audio. Use it to set up per-call state keyed by call_id — or, when reconnect is true, to restore it and resume streaming.

Schema

Field	Type	Description
`type`	string	Always `"call_connected"`.
`call_id`	string	Dial’s call identifier — the same value as in the connection path. Stable across reconnects. The only call id you receive.
`direction`	string	`"inbound"` if someone called your Dial number; `"outbound"` if the call originated from your account.
`from`	string	Calling phone number, E.164.
`to`	string	Called phone number, E.164.
`instruction`	string \| null	The instruction the call was placed/answered with, if any — useful as your model’s system prompt. `null` if none was set.
`language`	string \| null	The call’s primary language, BCP-47 (e.g. `en-US`). `null` if unset.
`formats`	object	The audio formats in effect: `{ "inbound": <format>, "outbound": <format> }` — see Audio formats. `inbound` is what Dial sends you; `outbound` is what you must send back.
`reconnect`	boolean	Absent or `false` on the first connection of a call; `true` when Dial re-established a dropped socket mid-call. Restore state instead of initializing.

Example

{
  "type": "call_connected",
  "call_id": "call_01HW3X7P5QF6K2YQ9YJ7Q8R5N3",
  "direction": "inbound",
  "from": "+14155550123",
  "to": "+14155559876",
  "instruction": "Answer billing questions for Acme Corp.",
  "language": "en-US",
  "formats": { "inbound": "mulaw_8000", "outbound": "mulaw_8000" }
}