Unable to join Microsoft 365 Developer Program Error Code: 40318 Country Code: +599 (Curaçao)

Question

Issue: Unable to join Microsoft 365 Developer Program Error Code: 40318 Country Code: +599 (Curaçao) Details: Valid Curaçao mobile numbers are rejected as “not formatted correctly”, even though +599 is selectable in the country list. This blocks signup completely.

Answer 1

Dear chepa rojer

Thank you for posting your question in the Microsoft Q&A Forum and sorry for late rely.

Please note that, as a forum moderator, I do not have access to the internal systems required to investigate individual account-related issues due to privacy and security constraints. In addition, the qualification and renewal process for Microsoft 365 Developer Program tenants is fully automated and based on predefined algorithms and telemetry. As such, I’m unable to manually reset or override Developer Program eligibility.

In your situation, I recommend reviewing the phone number format you’re entering. For Curaçao, phone numbers are commonly structured with an area code of “9” followed by a seven-digit local number. As a result, when the country code is selected as +599, the number may need to be entered in a format similar to: +599 9 6xx xxxx

If the issue persists, you may consider one of the following options:

1. If you have access to an account with a Visual Studio Professional or Enterprise subscription, try joining the Microsoft 365 Developer Program using that eligible account to unlock the Developer Program benefits (including the sandbox, when available for your eligibility).
2. Alternatively, you can sign up for a trial Microsoft 365 plan that matches your development requirements. If you choose a trial, please remember to cancel it before the trial period ends to avoid any unwanted charges (especially if you don’t plan to keep the subscription long-term).

Hope this information is helpful.

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Answer 2

Hi chepa rojer,

Thank you for reaching out to the Microsoft Q&A forum regarding the issue joining the Microsoft 365 Developer Program with Error Code: 40318 for country code +599 (Curaçao).

This error usually indicates a phone number validation or regional support issue on the signup system, not a problem with your number.

Steps to try

Enter the number without spaces or symbols Use the full format: +599XXXXXXXX

Try a different browser or private window Clear cookies or use InPrivate/Incognito mode.

Change verification method (if available) If SMS fails, select voice call or email verification.

Wait and retry later This error is often temporary and caused by backend validation rules.

Important note The Microsoft 365 Developer Program currently has limited support for certain country codes, and +599 may not be fully supported despite being listed. In such cases, signup can only be resolved by Microsoft internally.

Next step Please report this directly via the Microsoft 365 Developer Program support / feedback page so the team can correct the regional validation issue.

Thank you for your patience.