Hey @suzanne33640 - thanks for your post! Firstly, check out our New User Guide - it’ll def prove helpful as you get used to the platform!

SMS reminders are no-reply text messages that, even if your invitees do respond to, you will not receive responses for. 

In order to officially cancel a booking on the invitee’s end, they’d need to follow a cancel or reschedule link that you include for them. This can be automatically included in your booking confirmation and you can also choose to include it in a followup reminder email (this is the easiest way to achieve the goal) using Workflows. Alternatively (or additionally) you can include variables for cancelling/rescheduling via SMS - links for invitees to click on. This will take up much of the limited text space in your SMS reminders, so keep that in mind. In this case, an invitee would use that link to cancel - they will still not be able to “text you back” as the text is not coming from “you” - if that makes sense! See below!