Duplie can send out SMS/Text notifications to users with any paid plan. We do limit the SMS/Text depending on your plan. The most popular scenario is for sign up confirmations and reminders. In order for Duplie to send out SMS notifications, the user needs to give Duplie permission to do so. Users can configure their notification permissions in their account under Action - Settings and then click Permissions. Users have full control over what notifications they receive and HOW they receive them. Duplie can notify users via SMS/Text or Email.
As an admin, you can send notifications to users, groups, sign ups, etc. When sending a notification you will need to specify the permission to use. Choose the permission that is most closely related to your message. This determines if and how the user(s) receive this message.