- acquire-temporary-credential service #!optional callback-urlprocedure
This is the first step in the three step Redirection-Based Authorization defined in OAuth.
1. The client obtains a set of temporary credentials from the server (in the form of an identifier and shared-secret). The temporary credentials are used to identify the access request throughout the authorization process. -- RFC 5849, Section 2
If you are speaking OAuth 1.0a or RFC 5849 then you must specify callback-url at this stage rather than at the authorize-resource-owner stage.