Don't Hang Up!

Don't Hang Up! (1974) is a horror directed by S.F. Brownrigg rated 6.1/10.

13 years after witnessing her mother's murder by an unknown assailant, Amanda Post returns home to attend to her dying grandmother. When she dismisses the doctor, a local magistrate and an antique collector, all of whom seem to have their own sinister agendas, she becomes the target of anonymous threatening phone calls.