As of this posting Panasonic only officially supports five of this IP Camera with the KX-UT670. Link
All the manual says is that the camera must be set to VGA or 720p.
What it doesn’t tell you is that it only supports H.264.
I tested with the Panasonic WV-NW502S (Retails for over$1,000) and it worked fine.
Hopefully they will add support for their less expensive IP Cameras.
VoIP4EA 
can i connect an ip camera to work with an ip pbx