Your account's test credentials can be found on the API Keys & Tokens page in Console.
Scroll down to the Auth Tokens section to see your Test Credentials.
Overview
The Test Account SID and Test Auth Token are to be used with Twilio’s Magic Numbers to test your application's REST API requests. When using these test credentials, requests will be made to Twilio's API, responses will be returned normally, but no action will taken by Twilio.
Learn more about Test Credentials.