When you are using a test key with our API, only the connection will be tested and no messages or calls will be sent out. This allows you to check that your API has been set up correctly, without using your credits or balance. If there are any errors in your setup you can see this in the developer logs in your account.
If you want to start sending messages, you can create a live key for this. The live key will call our API, and send out a message accordingly and take the correct amount from your balance. You can use the live key in combination with test credits in your account.