---
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"@id": https://www.twilio.com/docs/api/errors/21421#article
headline: "21421: Phone Number is invalid"
url: https://www.twilio.com/docs/api/errors/21421
inLanguage: en
dateModified: 2026-03-11T18:38:39.000Z
author:
  "@type": Organization
  name: Twilio Developer Education Team
publisher:
  "@type": Organization
  name: Twilio
---

# 21421: Phone Number is invalid

Log Type: APPLICATION

Log Level: ERROR

## Description

You tried to purchase or lookup a phone number that is invalid or add a phone number to a Messaging Service with an invalid Phone Number SID.

### Possible causes

* You tried to purchase or lookup a phone number that is invalid.
* You tried to add an invalid Phone Number SID or Short Code SID to a Messaging Service.

### Possible solutions

* For phone number lookup or purchase, please specify a valid phone number in E.164 format.
* For adding a Phone Number to a Messaging Service, verify that the Phone Number SID or Short Code SID is correct and formatted properly, then retry the request.