Fatal error: Uncaught Error: Interface "Vonage\Client\Callback\CallbackInterface" not found in /home/demoweb/public_html/placementship-backend/vendor/nexmo/client-core/src/Client/Callback/Callback.php:23 Stack trace: #0 {main} thrown in /home/demoweb/public_html/placementship-backend/vendor/nexmo/client-core/src/Client/Callback/Callback.php on line 23