# 30126: Your 10DLC number failed to be registered 

Log Type: TWILIO

Log Level: ERROR

## Description

This error means Twilio could not complete the backend registration or deregistration of your US A2P 10DLC phone number. Number registration starts when you add or remove a number from a Messaging Service that is associated with an approved US A2P campaign. If the number reaches `FAILURE`, an unexpected error occurred during configuration with ecosystem partners.

### Possible causes

* The number registration or deregistration request reached the `FAILURE` status during backend configuration with ecosystem partners.
* The number was added to or removed from a Messaging Service associated with an approved campaign, which triggered a new number registration cycle that did not complete successfully. ([help.twilio.com](https://help.twilio.com/articles/19622397178139-A2P-10DLC-Number-Registration-Best-Practices))
* Repeatedly removing, re-adding, or moving 10DLC numbers between Messaging Services or accounts can trigger additional registration and deregistration cycles and lead to delays or errors. ([help.twilio.com](https://help.twilio.com/articles/19622397178139-A2P-10DLC-Number-Registration-Best-Practices))

### Possible solutions

* Request the A2P registration status CSV report in Console and verify whether the number is `FAILURE`, `PENDING_REGISTRATION`, `PENDING_DEREGISTRATION`, or `UNREGISTERED`. The report includes the phone number, Campaign SID, and Messaging Service SID so you can confirm the current state before taking action.
* If the number is `UNREGISTERED`, add it to a Messaging Service that is associated with a verified A2P campaign, then wait for number registration to finish.
* Avoid removing, re-adding, or moving the number while registration is being processed. Each change starts another provisioning cycle and can add more time or create additional errors. ([help.twilio.com](https://help.twilio.com/articles/19622397178139-A2P-10DLC-Number-Registration-Best-Practices))
* If the number remains in `FAILURE`, contact Support for investigation.

#### Additional resources

* [A2P 10DLC registration application quickstart](/docs/messaging/compliance/a2p-10dlc/quickstart)
* [Troubleshooting A2P phone number registration issues](/docs/messaging/compliance/a2p-10dlc/troubleshooting-a2p-brands/troubleshooting-a2p-phone-number-registration-issues)
* [A2P 10DLC Number Registration Best Practices](https://help.twilio.com/articles/19622397178139-A2P-10DLC-Number-Registration-Best-Practices)