In the User Profile, you can check - and manually modify if necessary - whether the contact is subscribed to your communications. In other words, you can manually subscribe and unsubscribe your contacts.

For example, if they accidentally unsubscribe by clicking the unsubscribe link and want to start receiving SMS again, you should edit their subscription status from here."

The example corresponds to a user who was suscribed when you did the data importation (accepts marketing: yes). and has not opted-out in any of your communications sent from Instasent. If after sending a campaign from Instasent, the user unsubscribes, the information will be automatically updated (accepts marketing: yes - Subscribed: no).

You can find a deeper explanation about what is the difference between "Subscribed to SMS" and "Accept SMS" Attribute here.