Richard Chamberlin plays a college professor who is trying to find out who is the psychopath (more like a postal ex-phone company worker) who is killing victim with a Hi-frequency sound through the phone. It kind of runs like a TV film, if you cut out the Phone/blood violence. John Houseman also star in this Canadian film that was released a year earlier in Canada as BELLS, and released in U.S. as MURDER BY PHONE. The American print is edited to 78 minutes as the Canadian print runs 95 minutes. Roger Corman probably edited it to save money on the print stock when he picked it up for U.S. release. Canadian print is recommended. Originally sold overseas under the title THE CALLING.