With their older speaker phone (forget the model), the salesman told me this beep was a "feature" - to remind you that you are muted, and that the Danes think listening with mute on is rude - something like you're talking behind someone's back. Yeah, I'd tell a story like that, too, but it did not sway me. I spend a lot of time listening to conference calls where mute is manditory so nobody hears my dog bark or kids yell (although most CC systems now have a key sequence to mute the line without muting the phone - maybe this is solution). Hence, I returned it... Then, the BeoCom3 came out, which didn't beep (the salesman was nice enough to remember that I wanted a speaker phone that didn't beep on mute and called me when it came out) so I bought and have enjoyed for many years. Unfortunately, the BeoCom3 was discontinued a while back.
Maybe they thought people didn't buy the BeoCom3 because it didn't beep on mute like their older phones so they added this "feature" back to the product 
I was contemplating replacing my BeoCom3 with a BeoCom5, but I guess not...
Stan