Telephony (SIP)
Telephony lets your voice agent answer phone calls: the saved agent bound to your number picks up, with its own model, voice, instructions, and tools. You bring the number and the system that carries your calls, and Mistral routes each call to your agent.
Telephony is available to enterprise customers, and it isn't self-serve. To enable it, contact your account team, or reach out to us.
How inbound calls reach your agent
Every call follows the same path, from the caller to your agent:
- A caller dials your phone number.
- Your SIP system, such as your carrier, an IP PBX, or a contact center platform, forwards the call to your Mistral SIP endpoint.
- Mistral starts a session from the saved agent bound to that number, and the agent answers the caller.
Before you request access, create the agent that answers your calls and save it. See Create and manage agents. You set up the number and your SIP system with the Mistral team: there's no configuration step to do on your side in the console or the API.
Design your agent for the phone
On a phone call, the caller's phone replaces the microphone and the speaker, and no code of yours runs during the call. Plan for these differences when you write the agent:
| On a phone call | What to do |
|---|---|
| Client-side tools fail, because there's no application to run their handlers | Give the agent server-side tools for anything it needs during a call, such as a document library or a connector to your systems. |
| The agent can't transfer the call to a person | Tell the agent in its instructions what to say when a request is out of scope, for example that a colleague will call back, and handle the follow-up in your own systems. |
| There's no screen: the caller only hears the agent | Keep answers short, and attach fillers to slow tools so the line doesn't go silent. |
Test the agent with a browser or SDK session before you put it on a phone line, and remove any client-side tool from it first. A tool that works in your test app fails for callers.
What you can build
Telephony fits phone lines where the questions repeat and the answers live in your systems:
- First-line support: answer common questions, check an order, and open a ticket. For example, answer common questions, check an order, and open a ticket.
- Appointment booking: take, move, or cancel a booking through a connector to your scheduling system.
- After-hours coverage: answer the calls your team can't take, and leave a summary for the next morning.
Security
Calls between your SIP system and Mistral are protected at the following levels:
- Transport:
- Authentication:
- Network:
Current limitations
Plan your phone service around these limits:
- Inbound calls only. The agent answers calls, and it can't place them.
- No client-side tools. Only server-side tools run during a call.