You're trying to verify your phone number on ChatGPT, Claude, or another AI platform, and you keep getting "Error sending code. Double check your phone number." You've checked the number three times. It's correct. But the code never arrives.
This error is almost never about typing the wrong number. It's usually a carrier issue, a formatting problem, or the platform's SMS provider not supporting your region. Here's what actually fixes it.
Quick Fixes (Try These First)
- Make sure you're including the country code (+1 for US, +44 for UK, etc.)
- Remove any spaces, dashes, or parentheses. Enter the number as pure digits: +11234567890
- Try again in 5 minutes. Rate limiting kicks in if you request too many codes in a row
- Check if your carrier blocks short code SMS (call your carrier and ask)
- Try a different phone number if you have one (second SIM, family member's number)
- Use WhatsApp verification if the platform offers it as an alternative
Most Common Fix
The most common fix is simply removing formatting from your phone number. Drop the parentheses, dashes, and spaces. Just country code + digits.
Why This Error Happens
| Cause | How Common | Fix |
|---|---|---|
| Wrong number format | Very common | Use +countrycode + digits only |
| Rate limiting (too many attempts) | Common | Wait 15-30 minutes |
| Carrier blocks short codes | Common | Call carrier or use different number |
| VoIP/virtual numbers not supported | Common | Use a real mobile number |
| Regional SMS provider issues | Occasional | Try WhatsApp or email verification |
| Platform outage | Rare | Check status page, wait |
Carrier-Specific Issues
Some carriers actively block short code SMS messages, which is what AI platforms use for verification. This is especially common with prepaid plans and MVNOs (smaller carriers that use bigger networks). T-Mobile prepaid, Cricket, and Mint Mobile users report this more frequently than Verizon or AT&T postpaid customers.
If you suspect a carrier issue, call customer support and ask them to enable short code SMS on your line. Some carriers have this disabled by default as an anti-spam measure. It takes about 5 minutes to fix on their end.
VoIP and Virtual Numbers Don't Work
Google Voice, TextNow, Skype, and most virtual phone numbers won't work for AI platform verification. The platforms specifically block VoIP numbers to prevent mass account creation. You need a real mobile number attached to a physical SIM card or eSIM.
Platform-Specific Tips
ChatGPT / OpenAI
OpenAI uses Twilio for SMS verification. If Twilio doesn't support your carrier or country well, you'll get errors regardless of what you do. Try using a number from a different carrier, or wait for OpenAI to expand their SMS provider coverage.
Claude / Anthropic
Claude's phone verification has been particularly problematic in some countries. If you're outside the US/UK/EU, you may need a number from a supported region. Check Anthropic's help docs for a list of supported countries.
If Nothing Works
- Try verifying at a different time of day (SMS services can be overloaded during peak hours)
- Use a completely different device (some apps cache failed verification state)
- Contact the platform's support team with your error details
- Ask if email-only verification is available for your region
If AI platform phone verification is a persistent problem for you, some platforms like Merlio offer alternative verification methods that don't require phone SMS, making signup easier for users in regions with unreliable SMS delivery.
Sources
- OpenAI Help Center - phone verification troubleshooting
Frequently Asked Questions
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