A Sandbox configuration allows you to test your Chat 2 Pay setup without using "real" money. It allows you to link your Chat 2 Pay configuration to a sandbox instance of your payment processor.
Where a production configuration is linked to a production payment gateway (i.e., when you click the payment link it renders a payment page that accepts real credit cards), you can use test cards on the payment gateway when using a sandbox configuration.

You can have multiple Sandbox Chat 2 Pay configurations in your account. To add a Sandbox configuration, navigate to My Workspace -> Chat 2 Pay in the Clickatell Portal and click New Sandbox Configuration.

Note: You cannot promote a sandbox configuration directly into production at this time. You will need to create a separate production configuration to use Chat 2 Pay in the production environment.