why do all the calls i attempt to make on my macbookpro fail?

On the MacBook Pro it gives you the option to make a call using your phone and it has been one of my favorite features bc I no longer have to have my phone by my side if im on my laptop... but lately every time I attempt to make a phone call it doesn't go through and when I receive phone calls my laptop rings but when I try and pick up the call it fails.. does someone know what it could be?