Phone number in form with area code

I wanted to create a form for my landing page where customers input their email and phone number. I was able to add in the form, then add the input, and then change the setting to ‘phone’ in the drop down.

However, if a customer just put in a number without their area code, it would be useless. Any one know how I can add in a section for the area code which then adds to the corresponding phone number?

Thank you!!