Fatal error: Uncaught Error: Class "Nexmo\Client\Callback\Callback" not found in /home/rpios/demo-stat.cymdev.com/vendor/nexmo/client/src/Message/Callback/Receipt.php:12 Stack trace: #0 {main} thrown in /home/rpios/demo-stat.cymdev.com/vendor/nexmo/client/src/Message/Callback/Receipt.php on line 12