Indicates the current state of modem. The meaning of each
state code is explained below:
unknown: the current state of the modem is unknown.
onHook: the condition similar to hanging up a telephone
receiver. The call cannot enter a connected state when
the modem is onHook.
offHook: The condition similar to picking up a telephone
receiver to dial or answer a call.
connected: The modem is in a state when it can transmit or
receive data over the communications line.
busiedOut: The modem is busied out (i.e. taken out of
service) and cannot make outgoing calls or receive incoming
calls.
disabled: The modem is in a reset state and non-functional.
This state can be set and clear via cmHoldReset.
bad: The modem is suspected or proven to be bad. The
operator can take the modem out of service and mark
the modem as 'bad' via cmBad.
loopback: The modem is in a state where it is currently
running back-to-back loopback testing.
downloadFirmware: The modem is in a state where it is
currently downloading the firmware.
downloadFirmwareFailed: The modem is not operational because
the downloading of firmware to it has failed.