If you decline the call, it will go to your personal voicemail. This is not a unique problem to SmartLine but instead a limitation when cellular service is used on top of another calling service. If you ignore the call (volume button) on your iPhone or let the call ring through it should go to SmartLine voicemail. If that is not happening, would you be willing to do a couple of test calls with us? If so, PM me your email and SmartLine #.