The iVvy system allows contacts to reply to SMS messages that you have sent from the system.
You can view these responses and unsubscribes by;
Navigating to Marketing > SMS Campaigns
Select “view” next to the campaign you wish to view the responses for, and then click to view the replies and unsubscribes.
If a contact unsubscribes from an SMS campaign, it won’t unsubscribe them from HTML campaigns.
If you wish to resubscribe a contact you will need to email support to have the contact re-enabled as they have been added to a suppression list to ensure that you can't re-import a list that an unsubscribed contact is on, and then mistakenly email them again.