With Twilio when you have a trial account it doesn’t allow you to send sms to whichever number you want. In the trial account, you have to verify numbers to which you want to send SMS. However when you pay for Twilio it will allow you to send SMS to whichever number you want.
To customize the text on the booking form, navigate to Settings > Booking Form. Locate the booking form preview and click on the Questions? text to activate edit mode. Once in edit mode, you can update the text to suit your specific requirements.