When selecting text message for verification method, your site should ask for mobile number.

When setting up account, when entering the primary number, you should be asking what type of phone number is being provided. Then, when giving people the option of verification method, if they select text message, you should be asking them to provide a mobile number. Right now, it seems your site assumes that the primary number provided is a mobile number. In my case, my verification method couldn't be successfully tested because I had provided my home number as my primary number and there seems to be no way to go back and change the selected method (or at least I can't find it), which is frustrating.