How to PROVE that some Oracle Stored Procedure has been called without auditing it?

Question

I need to PROVE that some Stored Procedure has been called.

This is a third-party database, so:

• I can't ask to change SP
• I can't ask to audit anything
• I have no DBA access

This is what I have:

1) DO SOME THINGS ...
2) START FOO STORED PROCEDURE ...
   2.1) WAIT UTIL FOO COMPLETES ...
3) DO SOME OTHER THINGS ...

This is what I need:

1) DO SOME THINGS ...
2) START FOO STORED PROCEDURE ...
    2.1) RECEIVE A RESPONSE FROM ORACLE: "OK! FOO HAS BEEN STARTED!" ...     
    2.2) WAIT UTIL FOO COMPLETES ...
    2.3) RECEIVE A RESPONSE FROM ORACLE: "OK! FOO HAS BEEN FINISHED!" ...
3) DO SOME OTHER THINGS ...