Hume EVI (Empathic Voice Interface) vs Vogent API

Hume EVI (Empathic Voice Interface)

Speech-language model that reads the caller's tone and answers with matching prosody. One account-wide key, sent in the WebSocket and Twilio webhook URLs.

Vogent API

IVR detection and navigation models for outbound calls. No public changelog and no release found since January 2026.

Hume EVI (Empathic Voice Interface)

1. Create a config with a voice first, EVI 3 has no default
2. Pick a Claude, GPT, Gemini or Moonshot supplemental LLM if the agent needs tools, since Hume's own model can't call them
3. Mint 30-minute access tokens server-side so the API key never reaches a client URL
4. Turn on 'Do not retain data' and 'Do not use for training' at app.hume.ai before sensitive calls
5. Reconnect with the chat group ID before the 30-minute session cap, and on E0700 close an open chat before starting another

Vogent API

1. Send an idempotencyKey on POST /dials, a reused key returns 409
2. Create a call with callAgentId, plus toNumber and fromNumberId for phone calls
3. Tell the model when to emit <|transfer|>, since transfers fire on that tag
4. Verify webhooks with the HMAC in X-Elto-Signature
5. Expect new dials to fail at the workspace's concurrent dial limit until calls end