Twilio Error Messages

Twilio is the integrated phone system with Referins. If you have a Twilio number setup, you can use Twilio to call and send SMS communications to contacts. (If you don’t have Twilio setup, check out our other tutorials and videos!) Below, we'll explain how to find and understand the error codes that may appear so you can troubleshoot any Twilio issues you experience.

Part 1: What are Twilio Error Messages?

If an SMS is undeliverable or an outbound call cannot be made, the system may notify you with a 5-digit error code, such as 30003 or 21610. Twilio provides a thorough list of error codes. Still, it’s important to know the ‘gatekeeper’ determining message deliverability is the recipient/destination phone carrier (i.e. if you’re sending to Verizon, ATT, etc.). The phone carrier determines if a message is spam/phishing, if the number is a landline, or if there is another reason the message cannot be delivered.

Having a specific error code allows you to troubleshoot the specific reason the SMS or call failed. Twilio has a full library of error codes that explains each error, along with possible causes and solutions. Check out this link for details on each error code: https://www.twilio.com/docs/api/errors

You can review a particular error and then determine the appropriate course of action to resolve the issue.

Part 2: Where to Find Them

There are a few different places you may find Twilio error codes within the system.

Contacts Tab:

Within an individual contact record, in the center column, where you can view communication history, a failed outbound call or SMS will have a red triangle icon, as shown below. You can click on that to open the error code message, which gives you the code number 30008 (explained in depth in Part 3 below).

Workflow Execution Logs: 

Go to the Workflow in Automation > Workflows and click Execution Logs. Click on “View Details” to see whether the SMS was sent.

Campaigns (Deprecated feature):

You may also click on a campaign and click “show detail” to view the success/failures of a specific campaign event. In the pop-up window, under the Failed tab, the error code 30008 appears:

Part 3: Common Twilio Errors

Below is a list of commonly seen Twilio errors. Check out the list below for some of the most common errors you may experience, and be sure to check out Twilio’s error message library for a more extensive list of every error code, possible causes, and potential solutions.

• Error 21610: the destination/recipient number has opted out of messages. They’ve unsubscribed or replied STOP, and they will need to reply START to resolve this issue.
• Error 30003: unreachable destination handset. This means the destination/recipient is currently unable to receive messages (unlike 30006 which indicates a permanent situation like a landline, 30003 is more often temporary.) Perhaps the phone is powered off, on airplane mode, or out of signal range.
• Error 30005: unknown destination handset. This means the number could be off/out of range, it could be a landline, or it could be a number not in service.
• Error 30006: the destination/recipient number is unreachable (most likely as a landline).
• Error 30007: message filtered. Phone carriers may flag and filter messages that appear to be spam, phishing, or fraud. This message could be filtered due to violating Twilio’s Messaging Policy or Acceptable Use Policy or could be filtered by the carrier due to their specific rules. 
• Error 30008: generic error. When a carrier partner notifies Twilio of a generic error to deliver a message without a detailed explanation, Twilio will return a 30008 code.

FAQ

Q: What should I do if I receive Twilio error code 21610?

A: Error code 21610 indicates that the recipient has opted out of receiving messages by replying "STOP" or unsubscribing. To resolve this issue, the recipient needs to reply "START" to re-subscribe and receive messages again.

Q: How can I address error code 30003?

A: Error code 30003 means the recipient's phone is temporarily unreachable, which could be due to the phone being powered off, in airplane mode, or out of signal range. Wait and try sending the message again later.

Q: What does error code 30007 signify, and how can I handle it?

A: Error code 30007 means the message was filtered by the carrier as it might be considered spam or phishing. Review Twilio’s Messaging Policy and Acceptable Use Policy to ensure compliance, and consider adjusting your message content to avoid being flagged.

Q: What does error code 30008 represent, and what should I do about it?

A: Error code 30008 is a generic error code indicating a delivery issue without a detailed explanation. Check Twilio’s error message library for further insights, and review your message and recipient details for any possible issues.