facetime on MAC with external camera rings, but doesn't connect
Trying to set my Boss up with an external conference camera (logitech BCC950) on his MAC for Facetime.
We can select the external webcam, speaker & mic in facetime preferences no problem and camera etc works.
Making a call in facetime, rings the contact OK, as soon as they answer the call - the session disconnects.
Making a call using the builtin camera is fine.
Skype calls work fine with the logitech, so there isn't an issue with the hardware\compatability (camera is listed iOS compatible).
Don't know if this is related,but the MAC wont receive a facetime call either. It doesn't ring, yet iphone and ipad right next to it ring no problem.
Any assistance welcome (I'm not a MAC user so please be gentle!)
iMac, OS X Yosemite (10.10.4)