By default, the system provides a touch call button (i.e. extension number). With this license, you will be able to add other buttons to the licensed external panel according to your needs. Just purchase a license for the number of buttons you add. If you have more than one licensed panel, you can assign any number of buttons in the purchased license. What does it mean? Having bought a license for 10 buttons, you can, for example, decide to add 6 buttons to one licensed panel and 4 buttons to another. Panels with an IpDoor license must not have the same number of buttons.