Claude Phone Verification Code Not Sending? Fix SMS Issues

Why Claude requires phone verification

Anthropic requires a verified phone number when creating a Claude.ai account to prevent spam, bot creation, and platform abuse. This is a one-time security check, but security filters can sometimes block legitimate users. If you are not receiving the SMS verification code, or if you receive an error message when submitting your number, it is usually due to carrier restrictions, virtual phone number blocks, or input formatting issues.

Follow these troubleshooting steps to resolve phone verification issues on Claude.

How to fix phone verification errors

1. Verify your phone number type Claude’s security system automatically screens phone numbers to prevent abuse. If your number falls into any of the following categories, the verification system will block it:

• VoIP and Virtual Numbers: Numbers from services like Google Voice, Skype, Zoom, or Twilio are not accepted.
• Burner or Temporary Numbers: Disposable online SMS numbers are strictly blocked.
• Landlines: The number must be capable of receiving SMS text messages.
• Prepaid Plans without Registration: Some prepaid SIM cards that lack verified identity profiles may trigger security blocks.

Ensure you are using a standard, contract-based mobile number from a major telecommunications carrier.

2. Correct your country code and formatting Incorrect number formatting is a common reason for SMS dispatch failures.

1. Select your correct country from the dropdown flag menu. Do not manually type the country code into the phone number field.
2. Enter the rest of your number without the leading zero. For example, if your UK number is 07123 456789, select the UK country code (+44) and enter 7123456789.
3. Remove any spaces, hyphens, parentheses, or extra symbols.

3. Check for carrier and delivery issues If the system says the code was sent but it never arrives, your network carrier might be filtering the message.

• Disable spam blockers: Many modern smartphones have built-in spam protection apps (like Truecaller or carrier-specific apps) that automatically filter out automated SMS codes. Temporarily disable these filters.
• Check roaming settings: If you are traveling internationally, ensure your phone is set up to receive international SMS over roaming, or connect to a local cellular network.
• Restart your device: Restarting your phone can force a reconnect to the nearest cell tower, resolving delayed SMS queues.

4. Clear browser data and use incognito mode Sometimes a cached session error on Claude.ai prevents the verification page from executing correctly.

1. Open a new private or incognito window in your browser.
2. Navigate directly to claude.ai/login.
3. Attempt the login and verification process again.
4. If this fails, try using your mobile phone's cellular data connection (turn off Wi-Fi) to rule out network-level IP blocks.

Common verification error messages

• "Invalid phone number" or "Unsupported number type": The system has flagged your number as VoIP, landline, or a virtual carrier. You must use a standard mobile number.
• "We are unable to send a code to this number": This occurs when your number has been blacklisted due to multiple rapid attempts, or your specific mobile carrier is experiencing a routing block with Anthropic's SMS gateway provider.
• "Too many verification attempts": You have triggered a temporary security lockout. Wait exactly 24 hours before trying again. Attempting to resend codes during this lockout window will reset the timer.

When to escalate to Anthropic support

If you have verified that your number is a standard post-paid mobile line, you have formatted it correctly, and you still cannot receive the SMS code after 24 hours, you must contact support.

To file a ticket, visit the Anthropic Support Portal and select "Account Access & Login Issues". Provide your mobile carrier name, your physical location, the phone number (including country code), and the exact error message you receive.