In order to activate MessageBird notifications you need to go under Settings -> Modules -> Notification Modules. Then, you have to click 'Activate' tab next to MessageBird notifications module. To configure the activated module, you ought to go under Settings -> Modules -> Notification Modules -> [MODULE] -> Edit Configuration.
Configuring module
Sign in to MessageBird.
Go to the Developers tab.
Select API Access (REST) and click button "Add access key".
Enter any description and select your access key mode (Live or Test).
Generated key, paste into HostBill module.
Eneter your originator name in HostBill module.