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Twilio Error 21418

The 'From' phone number is not a valid mobile number.

Understanding Twilio and Its Purpose

Twilio is a cloud communications platform that allows developers to programmatically make and receive phone calls, send and receive text messages, and perform other communication functions using its web service APIs. It is widely used in applications that require SMS communication capabilities, providing a reliable and scalable solution for businesses and developers.

Identifying the Symptom: Error 21418

When using Twilio's SMS API, you might encounter the error code 21418. This error typically manifests when attempting to send an SMS message, and the operation fails with a message indicating that the 'From' phone number is not a valid mobile number.

What You Observe

Upon sending an SMS, you receive an error response from Twilio's API. The response includes the error code 21418, and the message states that the 'From' number is invalid.

Understanding the Issue: Error 21418

Error 21418 is triggered when the 'From' phone number specified in your API request is not recognized as a valid mobile number by Twilio. This can occur if the number is not SMS-capable or if it is not a Twilio-verified number.

Root Cause Analysis

The primary cause of this error is using a phone number that either does not belong to Twilio or is not configured to send SMS messages. Twilio requires that all 'From' numbers be SMS-capable and properly configured within your Twilio account.

Steps to Fix Error 21418

To resolve this issue, follow these steps to ensure that your 'From' number is valid and SMS-capable:

Step 1: Verify Your Twilio Number

Log in to your Twilio Console and navigate to the Phone Numbers section. Ensure that the number you are using is listed under your active numbers and is marked as SMS-capable.

Step 2: Use a Valid Twilio Number

If the number is not listed or not SMS-capable, you will need to purchase a new number from Twilio that supports SMS. You can do this by clicking on Buy a Number in the console and selecting a number with SMS capabilities.

Step 3: Update Your Application Code

Once you have a valid SMS-capable Twilio number, update your application code to use this number as the 'From' field in your API requests. Ensure that the number is formatted correctly, including the country code.

Additional Resources

For more information on managing Twilio numbers, visit the Twilio Phone Numbers Documentation. If you continue to experience issues, consider reaching out to Twilio Support for further assistance.

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