So you’re signing up (or logging in) to Claude AI, and you hit a roadblock: “Error sending code. Double check your phone number.” Frustrating, right? Especially when you’re ready to dive into prompts or experiments with the AI.
This issue is more than just a glitch — it blocks access to Claude AI entirely until resolved. In this article, I’ll walk you through why this error appears, real-user experiences, and tested fixes (with explanations) so you can finally get past phone verification and use Claude AI without headache.

By the end you’ll understand:

• Why Claude AI demands phone verification

• What exactly causes that “error sending code” message

• Step-by-step troubleshooting you can try

• When and how to contact support

Let’s get started.

Why Claude AI Requires Phone Verification

Before jumping to the error, knowing why the system wants your phone number helps to understand the logic behind the checks and limitations.

Security and Abuse Prevention

Many online platforms use phone verifications (via SMS) to deter bots, spam accounts, or mass signups. Claude AI (by Anthropic) uses this as a guardrail to ensure real users are behind each account. The phone number acts as a second factor tied to your identity.

Recovery & Account Integrity

If you ever lose access, need password recovery, or want to enable two-factor authentication (2FA), the phone number can be crucial. It helps in verifying you legitimately own the account.

Regional Availability & Compliance

Claude AI currently supports phone verifications only in certain supported countries. If your country is not on the list (or if Claude restricts it), you may run into errors. According to Anthropic’s support docs, they do not support VoIP numbers or landlines for verification.

Hence, if you’re in an unsupported region or using an unsupported type of number, the system rejects the error before even sending a code.

Understanding the Error: “Error sending code. Double check your phone number. Claude AI”

This is a generic error message that shows up when Claude AI fails to send a verification SMS. But the root causes could be varied. Let’s break them down.

Common Root Causes

1. Incorrect Phone Number Format

• Missing or wrong country code

• Extra digits, leading zero, or formatting with dashes/spaces that the system can’t parse

• Typo in one digit

2. Unsupported Number Type

• VoIP / virtual numbers (e.g., Google Voice, Skype numbers) often get rejected

• Landlines (without SMS support)

• Numbers already flagged by the system

3. Region / Country Restrictions

• If Claude AI does not allow registration from your country, SMS may never go through

• Even if you’re physically in a supported country, your IP or account region might get flagged

4. SMS Filtering or Carrier Blocking

• Your carrier might block automated or short-code SMS

• Your phone’s spam filters, blocked senders list, or message settings might catch the verification SMS

5. Browser, Network, or Device Issues

• A browser extension (e.g. ad blocker, script blocker) may interfere

• Using a VPN or proxy might conflict

• Unstable Internet connection

• Browser cache/cookies interfering

6. System / Rate Limit or Temporary Outage

• Claude’s backend might have a glitch or downtime

• If you repeatedly requested codes in short time, you may be temporarily blocked

Real-Life Examples & What People Faced

• On Reddit, multiple users reported the system failing on Firefox, while it worked when they switched to Chrome or Edge.

• One user said their Taiwanese number wouldn’t get verified no matter what.

• Another user in Pakistan reported the same: even after adding country code, Claude AI rejected the number.

• A common tip emerging from these threads: try verifying from your phone rather than PC — in some cases, the mobile interface bypasses certain browser-related restrictions.

These anecdotes reinforce that sometimes the issue isn’t with your number, but with how/where you’re entering it (device, browser, etc.).

Step-by-Step Fixes: How to Resolve It

Here’s a structured approach you can follow. Try steps in order; many users get unstuck early in the list.

1. Double-Check the Phone Number Format

• Confirm country code (e.g., +1 for US, +92 for Pakistan)

• Remove any extra zeros or leading “0” after the country code

• Avoid spaces, hyphens, or symbols if the input field doesn’t allow them

• Re-enter fresh (don’t copy-paste with hidden characters)

2. Try Another Mobile Number (Non-VoIP)

If you have a different SIM (on your own or from a friend), try that. Make sure it’s:

• A regular mobile number (not VoIP)

• On a carrier known to receive SMS reliably

3. Clear Browser Cache / Cookies & Use a Clean Browser

• Clear cache and cookies

• Open private/incognito window

• Turn off browser extensions that block scripts

• Try in a different browser (Chrome, Edge, Safari, etc.)

Many reports show Firefox was the culprit in some setups.

4. Disable VPN / Proxy / Tunnel

If you use a VPN, proxy, or privacy IP routing, disable it while verifying. Your IP location should align with your phone number region.

5. Restart Device & Try a Different Network

• Restart your phone or computer

• If on WiFi, try mobile data; if on mobile data, try WiFi

• Use a stable, reliable network

6. Wait Before Retrying (Rate Limits)

If you’ve tried multiple times quickly, Claude might impose a cooldown. Wait 15–30 minutes before trying again.

7. Check SMS / Spam Filters

• Inspect your phone’s spam or junk SMS folder

• Ensure your messaging app isn’t blocking unknown senders

• If your carrier offers SMS filtering, check blocked lists

• Contact your carrier to confirm they’re not blocking short-code or automated SMS

8. Use “Continue with Google” (If Available)

Some users reported success by first signing up with Google SSO (Single Sign-On), then entering their mobile number later in the flow.

If that option is on the signup page, use it as it sometimes bypasses mobile-only flows that cause the error.

9. Use a VPN Strategically (With Caution)

If you’re in a country where Claude isn’t officially supported, a VPN may help mask your location to appear as though you’re in a supported region. But be cautious — using a VPN can violate terms of service, and some systems detect VPNs.

10. Contact Claude / Anthropic Support

If none of the above work:

• Provide your phone number (partially, for privacy), region/country, and what you tried

• Ask for a manual SMS to be triggered (if possible)

• Support might also reveal if your number is blacklisted or flagged

Claude’s official help center has relevant articles:

• I didn’t receive my phone verification code

• Phone verification and supported number info

Tips & Precautions (When Dealing With Verification)

• Avoid VoIP / virtual numbers — Claude’s system explicitly doesn’t support them in many cases.

• Don’t request excessively — too many requests in a short span may trigger rate limits

• Keep your number private — once verified, you don’t usually need to re-enter it unless account settings change

• Mobile-first approach — using the mobile app or mobile browser sometimes yields fewer errors

• Check for regional announcements — Claude may change available countries, so an unsupported region now might become supported later

Sample Flow: How It Worked for a User in Pakistan

Let’s go through a fictional but plausible scenario to bring this to life.

User: Ali in Faisalabad, Pakistan
Issue: When Ali enters +92 300 1234567, Claude shows “Error sending code. Double check your phone number.”
What he tries:

1. He re-enters without spaces, ensuring country code +92 and correct number.

2. He switches from desktop to his phone browser — still fails.

3. He disables his VPN (he was using one).

4. He clears cookies/cache, and opens the site in Chrome mobile.

5. Because Pakistan may not be fully supported, he tries a VPN endpoint in the UK (temporarily).

6. He also uses “Continue with Google” if prompted.

7. If it still fails, he contacts support including: country, number format, attempts made.

After doing this, he finally receives the SMS and verifies the account — success.

That pattern—checking format, switching device, disabling VPN, clearing cache, contacting support—is exactly what many users share in forums.

Why Some Workarounds (Not Always Recommended) Are Mentioned

Because users are desperate, you’ll find guides suggesting:

• Using disposable or temporary numbers (SMS services)

• Bypassing verification systems

• Using “unofficial” signup routes

However:

• These often violate terms of service

• You may lose access or recovery options later

• Support may refuse to help accounts verified via suspicious means

It’s safer to stick with official routes unless all else fails—and then use such methods with caution, fully aware of the risks.

In Summary / Conclusion

The dreaded “Error sending code. Double check your phone number. Claude AI” message usually stems from:

• A misformatted or incorrect phone number

• Unsupported number types (VoIP)

• Region / country restrictions

• Carrier or SMS filtering issues

• Browser, network, or device complications

• Temporary system limits or outages

To fix it, methodically go through:

1. Validating your number (with country code)

2. Using a different non-VoIP mobile number

3. Clearing browser cache, switching browsers

4. Turning off VPN / proxy

5. Restarting device, switching network

6. Waiting, checking SMS filters, contacting carrier

7. Trying “Continue with Google” (if option exists)

8. Reaching out to Claude/Anthropic support

With patience and the right steps, many users get past that roadblock and finally get full access to Claude AI.

If you like, I can even generate a custom checklist for your country (Pakistan) — step by step — to help you bypass the error. Want me to prepare that for you?

FAQs

Q1. Why does Claude AI reject my phone number even though it’s valid?

Because the system may not support your country or your number type (VoIP, landline). Also, misformatted country codes or cached session issues can cause rejections.

Q2. Can I use a virtual number or Google Voice?

Usually not. Claude AI’s system often blocks or rejects VoIP / virtual numbers.

Q3. Does switching browsers help?

Yes, many users fixed the issue by switching from Firefox to Chrome, Edge, or another browser.

Q4. If I live in a country where Claude is unsupported, is it hopeless?

Not necessarily. Some users had success using a VPN (carefully) or using alternative access platforms. But that comes with risks (account suspension, TOS violation).

Q5. When should I contact Claude support?

After trying the major fixes (correct format, no VPN, new browser, alternate number). Provide them your country, the number you attempted, timestamp, and the exact error.