---
"@context": https://schema.org
"@type": TechArticle
"@id": https://www.twilio.com/docs/api/errors/21218#article
headline: "21218: Invalid ApplicationSid"
url: https://www.twilio.com/docs/api/errors/21218
inLanguage: en
dateModified: 2025-12-18T21:40:49.000Z
author:
  "@type": Organization
  name: Twilio Developer Education Team
publisher:
  "@type": Organization
  name: Twilio
---

# 21218: Invalid ApplicationSid

Log Level: ERROR

## Description

You attempted to initiate an outbound phone call with an invalid ApplicationSid. The application may not exist anymore or may not be available within your account.