@Vignesh Raj - Welcome to Microsoft Q&A and Thanks for reaching out.
In Azure, note the following:
Virtual or prepaid credit cards aren't accepted as payment for Azure subscriptions.
Debit cards aren't accepted as payment for Azure subscriptions in Brazil and Hongkong regions.
If you are a student, you can sign up an account without credit card.
https://azure.microsoft.com/en-us/free/students/
You can see the eligibility criteria in the below Url.
https://learn.microsoft.com/en-us/azure/education-hub/azure-dev-tools-teaching/program-faq#azure-for-students
You can see the payment troubleshooting page to see the issues related to your case.
https://learn.microsoft.com/en-us/azure/cost-management-billing/manage/billing-troubleshoot-azure-payment-issues
https://learn.microsoft.com/en-us/azure/cost-management-billing/manage/troubleshoot-declined-card
Hope that helps.
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