Drift now has a built-in phone capture question that validates for real phone numbers, to add those questions your LeadBot flow scroll down to find capture phone number. We've made LeadBot extra smart so if the person doesn't respond with the valid phone number it'll ask once more. Here's an example of what that interaction might look like. After the phone number is received Drift saves their number as a Drift attribute so you can pass it to your marked automation or CRM system.
