---
"@context": https://schema.org
"@type": TechArticle
"@id": https://www.twilio.com/docs/api/errors/21213#article
headline: "21213: Caller phone number is required"
url: https://www.twilio.com/docs/api/errors/21213
inLanguage: en
dateModified: 2025-12-18T21:40:49.000Z
author:
  "@type": Organization
  name: Twilio Developer Education Team
publisher:
  "@type": Organization
  name: Twilio
---

# 21213: Caller phone number is required

Log Level: ERROR

## Description

You attempted to initiate an outbound phone call, but you forgot to include a 'From' parameter. The 'From' parameter is required, and tells Twilio what Caller ID to use for the phone call.