Hi Godric Tampinco,
Welcome to Microsoft Q&A Forum, thank you for posting your query here!
Similar issue I handled it, couple of days back, where you need to contact our support via one of the contacts mentioned here (you can pick Philippines based contact) https://support.microsoft.com/en-us/topic/global-customer-service-phone-numbers-c0389ade-5640-e588-8b0e-28de8afeb3f2
This issue with phone number validation during Azure Subscription Sign up can be resolved by creating a support ticket and working with our Azure subscription team.
Create a support ticket and do share it for reference, so that I can track it internally, get this sorted for you.
Please do not forget to "Accept the answer” and “up-vote” wherever the information provided helps you, this can be beneficial to other community members.
If you have any other questions or are still running into more issues, let me know in the "comments" and I would be happy to help you