SQL & PL/SQL

Hello all, I hope you can help me out.

I need to call another stored procedure in another database? Is it possible?
I know you can call another stored procedure in the same package:

Var_SQL :='call SP_Tes (''' || Var_1 || ''',''' || Var_2 ||''')' ;
EXECUTE IMMEDIATE Var_SQL;

But how do call it if its in another database? I assume, I'd have to open a new connection to it, then call it...

Please help me. thanks