Build on Callr

Three ways to add voice and messaging to your platform. Pick one, or combine them.

REST API

Buy phone numbers, send SMS, manage recordings and audio files, and receive webhooks from your backend.

Call flows in YAML

Describe what happens on a call or an SMS: menus, forwarding, recording, HTTP requests. Run it on your numbers or from the API.

Voice AI & SIP

Answer calls with an AI agent, or connect your numbers to OpenAI, ElevenLabs, Vapi or your own PBX over SIP.

Recipes