Retell AI API · Endpoint removal
outbound_agent_id on POST /create-phone-number stops working
Stopped working
Calls to POST /create-phone-number, body parameter outbound_agent_id on Retell AI API stopped working on March 31, 2026.
What to use instead of these calls
Send outbound_agents instead: a list of {agent_id, agent_version, weight} entries whose weights sum to 1 (one agent: weight 1).
Calls it hits
POST /create-phone-numberbody parameter outbound_agent_id
After 03/31/2026, the deprecated single-agent fields will no longer be supported.
Facts
- API
- Retell AI API
api.retellai.com - Kind
- Endpoint removal
- Takes effect
- March 31, 2026
- Calls after that day
- Fail
- Source
- Announcement
- Last updated
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