Hello,
Thank you for posting in the Microsoft Community Forums.
Please follow these steps to troubleshoot:
Double-check that you've entered the complete phone number, including the area and country code,
Make sure that the phone number you entered meets the requirements specified here. Troubleshoot issues when you sign up for a new account in the Azure portal - Microsoft Cost Management | Microsoft Learn
The phone number that you enter for verification isn't stored as a contact number for the account.
A Voice-over-IP (VoiP) phone number can't be used for the phone verification process.
Check that your phone can receive calls or SMS messages from a United States-based telephone number.
If you've already checked these things and are still having trouble, it's possible that there may be a delay in the verification process. Although the sign-up verification process is typically quick, it may take up to four minutes for a verification code to be delivered.
If you're still having trouble, you can try the Call me option instead of the text message option. If your phone doesn't receive text messages (SMS), this option may work better for you.
Best regards
Yanhong Liu