Then send the form to your attendees and invite them to sign up for text alerts. They can also choose to be added to your MailChimp list if they're not subscribers already.
Update your attendees on things like venue changes and parking issues. They'll receive your messages from a private Gather number to protect your privacy.
Anyone who has questions or feedback about your alerts can reply directly to you. When the event is over, Gather deletes their numbers to protect their privacy.