- I watched it in the 90's on TV, the movie or possible TV episode was most probably from the 80's.
- It was in colour and I'm quite sure it was American.
- The protagonist was a young woman, living alone in a big American city and afraid to leave her apartment because she believed that there is a killer that wants to kill her. I don't remember if this was related to her past or not.
- I think she felt she was being watched and she was receiving calls with no one talking.
- I think at some point she called a friend or relative to to talk about her fears.
- Near the end of the movie she was somehow forced to leave the apartment. I remember a scene in a dark alley where she overcame her fear. I think she was attacked there and managed to defend herself, unfortunately I don't remember if there really was a killer or she was attacked by a robber, etc.
- What may help is that I remember that all the scenes took place at night.
I think there were some scenes (at least one) shot in a way that suggested that the woman was being watched through a window from an apartment on the other side of the street. It was as if we were seeing through the eyes of the killer that was looking through his window and watching the woman through a window in her apartment. The killer was not shown though.
It's not: Midnight Lace, Copycat, Sleeping with the Enemy, Scissors with Sharon Stone, Windows with Talia Shire, Fear Inside with Christine Lahti, Tales from the Crypt episode with Blythe Danner in a library, Dream Lover with Kristy MacNichol, After Midnight with Marg Helgenberger, Wait Until Dark, Sorry, Wrong Number with Loni Anderson, When a Stranger Calls, When a Stranger Calls Back, Frozen With Fear, The Eyes of Laura Mars, The Night Caller episode of Alfred Hitchcock Presents, Lady Beware, The Fan (1981), The Seduction or Lisa.
The closest match so far seems to be Carpenter's Someone’s Watching Me! from 1978, but it's lacking the most important detail - the protagonist wasn't afraid to leave her apartment.