# inbound_agent_id on POST /create-phone-number stops working

Calls to POST /create-phone-number, body parameter inbound_agent_id on Retell AI API stopped working on March 31, 2026.

## What to use instead

Send inbound_agents instead, providing a list of entries with agent_id, agent_version, and weight fields whose weights sum to 1. For a single agent, set the weight to 1.

- API: Retell AI API (api.retellai.com)
- Kind: Parameter removal
- Takes effect: March 31, 2026
- Calls after that day: fail
- Calls it hits: `POST /create-phone-number`, `body parameter inbound_agent_id`
- Source: [Announcement](https://docs.retellai.com/deprecation-notice/2026/03-31_phone_number_agent_fields)
- Verified: November 6, 2026, against Retell AI API's own pages
- Page: https://www.okapi.bot/providers/retell-ai-api/breaking-changes/inbound-agent-id-on-post-create-phone-number-stops-working/

## Retell AI API's words

> After 03/31/2026, the deprecated single-agent fields will no longer be supported.

Okapi finds the calls this change hits in your repo and opens the pull request with the fix: https://github.com/apps/okapi-agent