[BUG] Phone verification in Viet Nam

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

Hello Anthropic Support,

I’m unable to verify my phone number during Claude signup. The system shows:
“Unable to send verification code to this number. Try a different number or try again later.”

I’m using a valid Vietnam mobile number in international format (+84983424010 and +84961835963 ).
Could you please check whether this number is blocked, rate-limited, or already linked to another Claude account, and help unlink/unblock it if possible?

Thank you.

<img width="643" height="398" alt="Image" src="https://github.com/user-attachments/assets/e7c15402-e635-458d-9203-4dc8b8cde7ed" />

What Should Happen?

Please help me unblock these phones

Error Messages/Logs

Steps to Reproduce

Please help me unblock these phones

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

Please help me unblock these phones

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_