OpenAI realtime · your SIP trunk · REST API

AI voice agents on your own SIP trunk

Kaleso places outbound phone calls through your SIP provider and connects them to an OpenAI realtime voice agent. Bring your own SIP trunk and OpenAI key, then call from the web app or a REST API.

Get started Read the API docs

From $19/month · 1,000 calls · Sign up with your email

1,000

calls per month

1

call at a time on Basic

$19

per month, Basic

AES-256

encrypted keys

How it works

From sign-up to your first AI phone call in four steps.

  1. Sign up

    Create an account with your email. We activate your subscription and you're ready to call.

  2. Add your SIP trunk and OpenAI key

    Save your SIP username, password and domain, and your OpenAI API key. Both are stored encrypted.

  3. Place a call

    Enter a number in the web app, or send a request to the API, and pick the OpenAI agent, an echo test or a WebRTC demo.

  4. Review every call

    Open the call history to see how each call ended and the SIP steps behind it.

Built for outbound voice AI

Everything between your SIP provider and an OpenAI realtime agent, handled.

OpenAI realtime voice agent

Bridge the call to an OpenAI realtime agent. Choose the model and voice and write the instructions the agent follows.

Your SIP trunk, your rates

Calls go out through your own SIP provider, so you keep your numbers, carriers and per-minute pricing. Save several connections and pick one per call.

Echo test and WebRTC demo

Check audio quality and latency with an echo call, or talk to the agent from your browser over WebRTC without placing a phone call.

REST API with API keys

Create API keys in Settings and place, list and end calls from your own software.

Call history with SIP events

Every attempted call is kept with its status, final SIP response and the SIP steps along the way, so failures are easy to explain.

Concurrent calls, encrypted keys

Run several calls at once, each on its own SIP and RTP ports. SIP passwords and OpenAI keys are encrypted with AES-256-GCM.

Simple pricing

You pay your SIP provider and OpenAI directly. Kaleso only charges for the platform.

Most popular

Basic

$19/month

Max 5 minutes per call

  • 1,000 calls per month
  • 1 call at a time
  • Calls up to 5 minutes each
  • REST API and call history
See pricing

Enterprise

Contact us

  • Custom call volume and concurrency
  • Priority support
  • Onboarding help
Contact us

Place calls from your own code

One authenticated request starts a call. Create an API key in Settings and you're set.

POST /calls
curl -X POST https://api.kaleso.cloud/calls \
  -H "Authorization: Bearer kal_…" \
  -H "Content-Type: application/json" \
  -d '{"phoneNumber":"+15551234567","sipConnection":"My SIP","target":"Open AI Agent"}'
Read the API docs

Frequently asked questions

What is Kaleso?

Kaleso places outbound phone calls through your own SIP trunk and connects them to an OpenAI realtime voice agent, an echo test or a WebRTC demo in your browser. You can place calls from the web app or through a REST API.

Do I need my own SIP trunk and OpenAI key?

Yes. Kaleso is bring-your-own: you add your SIP connection (username, password and domain) and your OpenAI API key in Settings. Your telephony minutes are billed by your SIP provider and your AI usage by OpenAI, so Kaleso only charges for the platform.

Which SIP providers does it work with?

Any provider that gives you SIP credentials, meaning a username, a password and a SIP domain. You can save several connections and choose one for each call.

How are my SIP password and OpenAI key stored?

They are stored encrypted with AES-256-GCM and are never shown again after you save them.

Can I place calls from my own code?

Yes. Create an API key in Settings and send a POST request to https://api.kaleso.cloud/calls with the phone number, the SIP connection and the target. The API documentation has curl, Python and Node examples.

What do I get in the call history?

Every attempted call is kept with its status, how it ended, the final SIP response and the SIP steps along the way, so you can see why a call failed.

How much does Kaleso cost?

Basic is $19 per month and includes 1,000 calls per month, one call at a time, up to 5 minutes each. For higher volume or more concurrent calls, contact us about Enterprise. See pricing.

Make your first AI call today

Bring your SIP trunk and OpenAI key. Be on a live call in minutes.

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