Call Waiting up to the Line Number

[macbeto]

Hi,

I would like to know if there is a way to limit the Call Waiting to the number of Lines that I have.
I mean I have setup 2 lines in my phone and I have enabled the Call Waiting feature my phone only can ring 2 simultaneous call, and the third call will receive a busy.
Right now I only have 2 options: call waiting enabled (and the phone receive unlimited calls) and call waiting disabled (and the phone only receive 1 call)

Thanks