More and more I've been seeing online services that want to verify my identity using an automated phone call or text message. The trouble is - they ask me to provide the phone number! It seems the only thing they've verified is that I own a phone. I suspect a skilled attacked could even use a "burner" phone or virtual number of some kind to make the verification anonymous.
I've also considered this might be a new type of CAPTCHA, but considering how easily a computer could parse the data, that seems unlikely.
Does the verification process actually add any value from a security standpoint?
EDIT: This is not just during sign up, it's used to verify existing accounts as well. See sample screenshot from G Suite (Google Apps for Bussiness). I signed into an account that does not have 2FA enabled from a computer I do not normally use to sign into the account. After entering my cell number, I got a verification text and was able to get in the account.