Integrate RingCentral

The RedirectURI is part of the application right from the Development phase in Sandbox. You would need to add RedirectURI's into your application once you begin development. 

Please take a look at another community article on how to add RedirectURI's:
https://devcommunity.ringcentral.com/ringcentraldev/topics/i-want-to-add-dynamic-oauth-redirect-url

For more information on OAuth2.0 Authorization Code Flow please take a look at this article:
https://devcommunity.ringcentral.com/ringcentraldev/topics/using-oauth-2-0-authorization-code-grant-...

Approval of your OAuth Redirect URI is implicitly in the graduation requirements because proper Redirect URI handling is necessary to make the requisite API calls to pass the graduation requirements.