This read-write BITS object controls detection of special modem tones on the module, currently defining only the vism1560980Tone bit, where setting the bit to 1 enables detection of the 1560/980Hz tone used in special encrypted-data modem calls. An admin cares because enabling this detection lets the gateway correctly recognize and handle encrypted modem traffic that uses this specific tone pair rather than treating it as ordinary voice. For example, an operator supporting secure modem devices that rely on 1560/980Hz signaling would set vism1560980Tone to 1 so the module detects and properly handles those calls.