I have a simple setup. 2 x FXO lines. 2 x 502 phones. I setup a call blast group (pilot #501) to ring both phones for 10 seconds then forward to extension 201's voicemail. Both phones ring no problem for 10 seconds but then the call disappears. The phone is still ringing on the external side but nothing is ringing or transferring on the UC520. I tried all the options for "no answer forward to" with the same results.