Thriller / Horror film.
Revolves around a ghost of a woman who lurks on a building balcony.
Protagonist moves into said house, and as events unfold, comes across a mysterious telephone line which leads to a secret room.
I think the protagonist has several visions or flashbacks regarding the past of the house, possibly something involving a baby or a child that used to live in the house.
Showed on Channel 5 many, MANY years ago. The film preview part (bit before film starts and before the ad breaks) was of the protagonist in a car, screaming, due to an approaching train.
The film ends with the protagonist moving out of the house, and as she leaves, she looks up to the roof of the house and sees the ghost woman on the balcony.
Literally, if anyone gets this, I will cry, as I have been trying to find this film for ages.