If messages are not being sent, what should be done?

If SMS messages are not sent to short numbers on Android phones:

Settings – Programs – Special access ( options) – Use premium text message services – Always Allow 
or 
Settings – Search settings – Type “SMS” – From the sections listed below, select “Premium SMS” – Always Allow

If SMS messages are not sent to all numbers:

To configure SMS settings on your phone, follow these steps in the phone menu: 

Messages – Settings – Text Messages – Message Center (choose SIM1 or SIM2) – Add the SMS Center number: +994509103300