An audio speaker is physically situated near the doorbell switch, for reproducing {HEAD ~ audio signals} from the telephone line which are generated at {TAIL ~ the remote telephone} 
An audio speaker is physically situated near the doorbell switch , for reproducing { HEAD ~ audio signals } from the telephone line which are generated at { TAIL ~ the remote telephone }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL