Fix Microsoft 365 Developer SMS Verification Failed (Error 40351)
Question details
Users are unable to complete SMS verification during the Microsoft 365 Developer Program setup, receiving a 'phone number did not pass security checks' message.
- Product
- Microsoft 365 Developer Program
- Device & OS
- not provided
- Scenario
- Setting up a Microsoft 365 E5 developer sandbox account.
- Observed behavior
- The SMS verification fails, displaying error code 40351 and a correlation ID, which prevents the account setup from continuing.
Ensure you take a screenshot or write down the specific correlation ID and timestamp shown on the error screen, as Microsoft Support will need this information if self-troubleshooting fails.
Disable VPN and Switch Network Connection
Microsoft's security systems often flag virtual private networks (VPNs) or proxy servers, which can trigger the 40351 error during SMS verification.
To prevent abuse, the Microsoft 365 Developer Program strictly checks the IP address against the region of the phone number provided. Using a VPN or a corporate proxy can cause a mismatch that results in failed security checks.
Turn off any active VPN connections, proxy settings, or custom DNS configurations on your device.
Disconnect from your current Wi-Fi network and connect to a different one, such as a mobile data hotspot, to obtain a fresh IP address.
Open a new Incognito or Private browsing window in your web browser to ensure no cached data or extensions interfere with the process.
Log back into the Microsoft 365 Developer Program and attempt the sandbox setup and SMS verification again.
Submit a Support Request via Microsoft Admin Center
If network adjustments do not resolve the issue, your number or account may require manual clearance by Microsoft Support.
Try WPS Office for Your Daily Productivity Needs
While waiting for Microsoft 365 Developer account verification issues to be resolved, you can use WPS Office. It is a free, lightweight, and comprehensive office suite that requires no complex sandbox setups or phone verifications to start creating and editing documents immediately.
- 1. Download the Installer: Visit the official WPS Office website and click the Free Download button.
- 2. Install WPS Office: Run the downloaded setup file and follow the on-screen instructions to complete the installation.
- 3. Start Creating: Open WPS Office and immediately start working on your documents, spreadsheets, and presentations without verification barriers.
Frequently Asked Questions
Why does Microsoft say my phone number did not pass security checks?
Microsoft's automated security systems flag certain scenarios to prevent spam and abuse in the Developer program. This happens if you use a VoIP number, a virtual number, or if your IP address location does not match the country code of your phone number.
Can I use a virtual phone number for Microsoft 365 Developer SMS verification?
No. Microsoft explicitly blocks most virtual phone numbers and Voice over IP (VoIP) services for developer account verification. You must use a standard mobile number provided by a mainstream telecommunications carrier.
What is a correlation ID in Microsoft 365?
A correlation ID is a unique identifier generated by Microsoft's servers for a specific error event. Providing this ID to support agents helps them locate the exact server logs related to your failed verification attempt, speeding up the troubleshooting process.
How long does a temporary SMS block last in Microsoft 365?
If you fail verification multiple times, Microsoft may temporarily block the number for 24 hours. Wait a full day before attempting the verification again to ensure the block is lifted.
