[Bug][Auth][VS Code] Phone verification blocked by `fraud_guard` for multiple legitimate Pakistani numbers

What issue are you seeing?

I am unable to complete ChatGPT sign-in for the official Codex VS Code extension because the phone verification step is rejected server-side.

I am using an existing paid ChatGPT account and selecting Sign in with ChatGPT (not the API-key flow). The authentication flow reaches the phone-verification page, but attempting to send a verification code fails with HTTP 400.

The backend response is:

{
  "error": {
    "message": "We've detected suspicious behavior from phone numbers similar to yours. Please try again later or contact us through our help center at help.openai.com.",
    "type": "invalid_request_error",
    "param": null,
    "code": "fraud_guard"
  }
}

The failing request is:

api/accounts/add-phone/send
HTTP 400

Steps to reproduce

1. Install/open the official Codex extension in VS Code on Windows.
2. Choose Sign in with ChatGPT.
3. Authenticate with the same account that works normally on ChatGPT web.
4. The OpenAI auth flow requests phone verification.
5. Enter a legitimate Pakistani mobile number (+92).
6. Submit the verification request.
7. The request is rejected with code: fraud_guard before any SMS is sent.

Troubleshooting already performed

• Tried my own legitimate mobile number.
• Tried additional legitimate mobile numbers from my household.
• All numbers return the same fraud_guard backend error.
• Tried Incognito/private browsing.
• Tried a different network/mobile data.
• VPN/proxy is not being used.
• Confirmed the phone numbers are entered in international format.
• ChatGPT web login itself works normally.

Because multiple unrelated legitimate numbers receive the exact same backend response, this appears to be an account/auth-session/risk-check issue rather than a malformed or invalid phone number.

Expected behavior

A legitimate phone number should be allowed to receive the verification code, or the authentication flow should provide a supported alternative verification method for an existing paid ChatGPT account.

Actual behavior

Every tested legitimate number is rejected by the OpenAI backend with HTTP 400 and code: fraud_guard, so Codex authentication cannot be completed.

Environment

• Product: Codex VS Code extension
• Authentication method: Sign in with ChatGPT
• OS: Windows 10
• Region: Pakistan
• ChatGPT account: paid subscription
• VPN/proxy: none

I am intentionally not posting any full phone numbers or other account-identifying information publicly. I can provide account-specific details privately to OpenAI Support if needed.

No repository file, test, or entry point is identified. Start by reproducing the Sign in with ChatGPT flow in the Codex VS Code extension and capture the api/accounts/add-phone/send response; done would require a supported fix for the fraud_guard rejection or an alternative verification path.