When this device is "on hook", the speech circuit is disabled & the ringing circuit is connected
... for an on-hook condition of a telecommunication circuit device 
coupled to... [DOC] [TLE] Using the HT95R6x for CID Phones - Holtek [PAR] Holtek's new HT95R64 and HT95R65 devices are 8-bit CID Phone MCUs with a 
CPT