With regard to regular radio reports, according to Otto Kretchmer (spelling ?) they knew the brits were monitoring and tracking all uboat/bdu radio traffic, and he states that he only radio'd when absolutely necessary.
If I'm not mistaken, this is how he got his nickname, 'Silent Otto'.
This also how I play the game... I only use the radio once I break off a convoy attack, otherwise you never hear from me.
