I can understand why others reacted rather unpleasantly towards the climax yielding a twist that really is hard to take seriously. I think, though, that the build-up to it works rather well. The music, quite menacing and spine-tingling, really provides a spooky aura matching the unforgiving sound of a constant ringing telephone that is driving struggling English actress, Joan Matlin(Jean Marsh)bonkers. She's borrowing a pal's nice apartment while attempting to jump-start her career in New York City(..the city buildings outside the window look about as realistic as David Letterman's)and is unceremoniously welcome by a noisy telephone which rings quite a bit, followed by loud slams against the wall. Searching for answers regarding the one responsible for such disregard towards her sanity, Joan discovers that no one rents that room, and that a former tenant had in fact strangled herself. Without help from the manager, Joan will decide to find out for herself who is causing her such anguish. Joan discovers the room empty and the phone with a particular female voice which will haunt her.<br /><br />The episode, I think, is a tour-de-force for Jean Marsh who is a one woman show. She's the only actress visible and we follow her through the crisis which slowly erodes her, the phone and the banging from that other room causing her much distress which grows into fear. Instead of leaving, Joan remains, so shaken by the noise and to the breaking point where she just wishes for the phone(..or whoever is ringing)to stop. The episode provides a possible answer as to who is plaguing Joan and why. A character named Beth comes into the story rather late as Joan struggles to find out whose female voice it was across the other line who knew her name on that dreaded phone she discovers in the room across from hers. The fate of Beth might just tell the viewer why Joan is being traumatized. I think this episode is an exercise in spooks instead of credibility;some didn't particularly like it, but I certainly did. I will admit that the phone, as a physical menace "crawling" towards Joan is hard to take seriously, not to mention it's attack on her, but I thought the intense opening twenty minutes before this were suitably chilling enough to make up for it.