Add Phone verification using an API to existing C# .NET & Angular JS Website & More future work

We have an existing C# .NET website and we'd like to have this integrated into our signup flow: [login to view URL] All we need is to add one more step to the signup wizard we have: - All this step shows is simply one input field for the user to enter their mobile phone number for verification with a button next to it that says "Verify Me". - When the user presses this button, the API will call their phone for 1 second. - Once the missed call has been made, another input field should appear underneath for the user to "Enter the last 5 digits of the phone number that just called you" with a button next to it that says "Verify Code". - When the user's code is verified, it will unlock the "Next" button (bottom right of wizard content). NOTE: The "Next" button should be disabled until the code verification button was clicked and it was verified successfully. We also want to build a connection with the developer/firm we hire for future work.