ciscoHealthMonUnavailableModems 1.3.6.1.4.1.9.10.28.1.2.1.8

The number of modems on a shelf that cannot accept the calls. They are in the following states: unknown, onHook, busiedOut, disabled, bad, or downloadFirmwareFailed. This is the polled value for cmSystemModemsUnavailable from the router shelf.