While automated email confirmations always are sent out to the guest by default, text messages however behaves differently. This option needs to be activated as you will be charged a small fee for each sent SMS.
1) First you need to activate the automated SMS function. This article describes how.
2) Then, by default, text messages or SMS, are only sent out if the guest check the box " in the booking form when the guest book the room on your homepage.
3) You can change this by forcing text messages to always be sent to guest, if activated in step 1, under "Settings -> Booking form -> General options for booking form -> Check the box under:
Select if text messages (booking confirmation and any automated messages) shall be enabled for new bookings by default.