Fatal error: Uncaught Error: Class 'Nexmo\Client\Callback\Callback' not found in /home/sophiadmin/public_html/developer/vendor/nexmo/client/src/Network/Number/Callback.php:33 Stack trace: #0 {main} thrown in /home/sophiadmin/public_html/developer/vendor/nexmo/client/src/Network/Number/Callback.php on line 33