Is there a setting to prevent contacts from unsubscribing or opting-out of receiving Everbridge SMS notifications?
No. SMS is a highly regulated environment in all countries for which Everbridge has a dedicated local SMS code. One of the requirements for being assigned a local code from these countries is that the messaging platform allows the owner of the mobile device to request no messages be sent to that device. This request can be accommodated in any reasonable manner, but all mobile phone companies in the world expect mobile phone owners to text a simple keyword to the message sender to request to be unsubscribed from further notifications. The SMS regulations do not take into consideration the types of messages being sent to an individual's device by any content provider.
In compliance with SMS regulations in all countries for which Everbridge has a local SMS code, Everbridge allows contacts to opt-out of receiving SMS messages by replying with certain keywords. You will not be able to disable or modify this feature for your organizations.
Please see knowledge base article EBS: SMS - Unsubscribe / Opt-Out / Remove / Stop From Receiving Everbridge SMS Notifications for information on how contacts and other message recipients, such as residents, can opt-out of receiving Everbridge notifications.