How do you call a pg procedure with parameters from C#?

the 100 examples and other related posts do NOT work. i.e. (How would I call a PostgreSQL 13 stored procedure from C#?)

here’s my super simple example:
table

    (col1 integer, 
    col2 character varying(20) )

proc

    create procedure proc1 (num int, str varchar(20))
    language plpgsql    
    as $$
    begin  
    insert into test1 (col1, col2) VALUES (num, str);
    commit;
    end;$$;

code

    using var cmd = new NpgsqlCommand("CALL proc1()", _con);
    cmd.Parameters.AddWithValue("num", NpgsqlDbType.Integer, 2);
    cmd.Parameters.AddWithValue("str", NpgsqlDbType.Varchar, "string");

    cmd.ExecuteNonQuery();

exception: Npgsql.PostgresException: ‘42883: procedure proc1() does not exist

POSITION: 6′

I also made a proc2 that has NO parameters and I’m able to call that one just fine. I also tried several variant to “CALL proc1()” like “CALL proc1(num, str)” but those exceptions make even less sense as pg can’t tell the difference between a parameter and a column: “Npgsql.PostgresException: ‘42703: column “num” does not exist”