Microsoft 365 Error Codes

How to Fix Microsoft 365 E5 Sandbox Error 40301 (Phone Security)

WPS Content Manager Oct 9, 2026 868 views

Question details

The user cannot complete the Microsoft 365 E5 developer sandbox signup due to a phone number security check failure.

How to Fix Microsoft 365 E5 Sandbox Phone Security Check Error 40301

Product: Microsoft 365 E5 Developer Program
Device & OS: not provided
Scenario: Signing up for a Microsoft 365 E5 developer sandbox account.
Observed behavior: The signup process fails with error code 40301, indicating the phone number did not pass Microsoft's security checks despite successful account verification.

Before you start

Have your MS-CorrelationId, error code 40301, and account details ready. Stop attempting to submit the signup form repeatedly, as this can trigger further automated security locks on your phone number.

Solution 1Recommended

Contact Microsoft Support to Resolve Error 40301

Because error 40301 is triggered by automated backend security systems, resolving it requires direct intervention from Microsoft Customer Support.

Repeatedly submitting the signup request will not bypass the security check and may result in your phone number being permanently flagged. The most effective way to clear the error is to contact Microsoft Customer Service directly by telephone.

Locate the Global Customer Service Number

Visit the official Microsoft Global Customer Service phone numbers page (https://support.microsoft.com/help/c0389ade-5640-e588-8b0e-28de8afeb3f2).

Select Your Region

Scroll through the list on the support page and select your specific country or region to find the appropriate local support telephone number.

Provide Necessary Details to Support

Call the support number and explain that you are experiencing Error 40301 during the E5 developer sandbox signup. Provide the representative with your MS-CorrelationId, account details, and state your training requirement.

Contact Microsoft Support to Resolve Error 40301

Check Community Threads: You can also review related Microsoft Community threads (such as thread b1812e16-afce-4ff2-9ea1-97a552906eb9) for updates from other developers experiencing the same security check block.

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Frequently Asked Questions

Why am I getting error 40301 during Microsoft 365 E5 signup?

Error 40301 occurs when Microsoft's automated security systems flag the phone number provided during the developer sandbox registration as a potential risk, blocking the signup process.

Can I use a different phone number to bypass error 40301?

You can try using a different, legitimate mobile phone number. However, using virtual numbers (VoIP) or repeatedly trying different numbers often triggers the same security check failure.

Will waiting a few days fix the 40301 security check error?

Sometimes the temporary block on your phone number may clear after 24 to 48 hours. However, if the system permanently flagged the number, you must contact Microsoft Support by phone to lift the restriction.

Microsoft Office Error Codes