Organizations have the ability to signup to send SMS messages to Guests. If this is a feature you're interested in please reach out to your Implementation Manager/CSM.
When a Guest Opts In to receive SMS messages they have the option to Unsubscribe from receiving SMS messages. There are several responses a Guest can respond with to Unsubscribe from receiving SMS, these responses are mandatory to comply with CTIA guidelines for US short code programs.
To see the START/Subscribe Responses review the article below:
To see the HELP Responses review the article below:
To confirm a Guest has been unsubscribed from SMS messages review the article below: