Why would a device with a static ip not respond to a ping, but still transmit information over the network?
In my situation the device is a very simple caller ID box. It has no GUI. It's only purpose is to parse CID information and transmit the information where applicable.
An ip capable device doesn't have to implement ping at all.
Especially very simple devices, with very limited functionality, don't do anything not strictly necessary for what they need to do.
It just keeps the software simple (less potential for bugs) and as tiny as possible (less ROM/RAM needed). As a result it will be cheaper to manufacture (in man-hours for programming/debugging and in material costs).
In bigger, more complex equipment the ip-stack is often bought as a, ready to go, commodity-module and the RAM/ROM needed is usually already present because of other requirements.
Then there is often a full ip-stack present, with a ssh or web-interface for configuration and other niceties, because it doesn't cost any extra to implement.
The device (or some intermediate device on the network) could be blocking ICMP traffic without blocking other traffic.
