If you want to run Ultimate SMS, you have to purchase sms gateway API from sms gateway providers like Twilio, nexmo, plivo, etc. There have more than 50+ sms gateway APIs already integrated with ultimate sms. You can choose one from these or you can also add your gateway with ultimate sms. Then you have to update your sms API credentials on ultimate sms. Finally, you can send your sms using your sms gateway API through ultimate sms.