Error code
30751: Brand Registration Failure: Unsupported mobile phone number
What this error means
The mobile number given for Sole Prop OTP verification isn't a supported type.
Causes, most likely first
- The number can't receive the verification SMS.
- The number was bought from a CPaaS provider (including Twilio itself), not supported for this step.
- The number doesn't otherwise meet Sole Prop OTP requirements.
Fields Twilio names for this error
Twilio’s page for this error names these submission fields:
mobile_phone_number
How to fix it
If your numbers are managed by a platform
If your numbers sit inside a reseller platform, for example LeadConnector numbers inside GoHighLevel, you do not have access to the Twilio Console, and the interface shows the rejection without the code. Ask that platform's support team for the Twilio rejection error code, in writing, before you change anything. You can also read it yourself from your browser, which is faster: see how to get the code.
The substance of the fix is yours to make: the business details, the website, and the opt-in flow described in the Twilio path all belong to you, not to the platform. Make those changes first, confirm they are live, then ask support to resubmit. A resubmission filed before the underlying facts change will fail again on the same reason.
If you own the Twilio account
Swap mobile_phone_number for a real wireless mobile that can receive the OTP, and make sure its owner will reply to complete verification. If the OTP lapses after 24 hours, trigger a fresh verification request. Resubmit once the number qualifies.
Timing and resubmission
OTP is valid 24 hours; letting it lapse means requesting a new one, not re-registering the brand.
Two ways forward
Have it handled for you
A2P registration is handled for you on Growth at $597/mo and on Scale at $1,197/mo. Registration, resubmissions, and the compliance work behind them are included.
Fix it yourself
Send your email and we will send the fix playbook for registration rejections.
Verified against Twilio documentation on 2026-08-10.