Amazon Linux 2023, PHP 8.4, Composer 2.8.12
TeleSign SDK version: v3.0.7
Error message: Class "telesign\sdk\Config" not found
Solution: Rename src/config.php to src/Config.php
curl -s https://raw.githubusercontent.com/TeleSign/php_telesign/master/src/Config.php
Does not find anything and
curl -s https://raw.githubusercontent.com/TeleSign/php_telesign/master/src/config.php
does.
Hope this saves others a few hours of debugging!