Cut Phone Lines

Sometimes, the villain knows what the heroes are planning to do and where they will go. In this case, said villain knows when they will have access to a phone. So, to avoid having the police interfere, he (or she) will cut the phone line, often offscreen.

Stock Phrase uttered by someone who is in danger and has just realized what has happened.

Frequently a Horror or a Mystery movie trope. Since cell phones have made this largely obsolete, this is generally replaced by Can You Hear Me Now in modern works.

Anime and Manga

 * In Saitama Chainsaw Shoujo, Kirisaki Fumio makes a point of cutting the phone lines and disabling the local cell towers around her school to maximize the time she can spend cutting apart her classmates with a chainsaw before the police notice.
 * In Monster, Johan does this before

Comic Books

 * Also, Lucky Luke did this trope with telegraph lines, because it is set in the Wild West. On one occasion the (fictitious) Indian tribe Blue Foots cut off a telegraph mast, while a telegram is send for Luke to the cavalry. Another time it was the so-called real Dalton Brothers who shot the telegraph lines to keep another city from learning about their arrival.
 * In The Dragon Doctors, one of the first thing bandits do when attacking is jam all communications. The second time it happens, it actually alerts Goro of the impending attack.
 * In the third issue of The Adventures of Dr. McNinja, Ronald McDonald says he's going to call the police about the crazy man robbing from his secret hamburger warehouse (don't ask), then one of the raptor banditos (don't ask) gives a very badass speech about why Ronald should just let them handle it instead of getting the police involved. And then Doc McNinja says that it's a moot point because he cut the phone lines.

Film

 * The first Die Hard movie shows the bad people doing this. They weren't planing on physically cutting, but a guy got impatient.
 * The Matrix has a variation: Cell lines are ubiquitous so communicating is not a problem, but to actually get out of the matrix, you need a hard line. A virtual hard line. A hard virtual... look it's gotta be a phone line so cutting the phone lines is serious.
 * The Incredibles had this on its collector's edition DVD, which included animated storyboards of deleted scenes. One featured an alternate situation where Syndrome tracked down the Parr family when Violet was still a baby. When Helen attempts to dial 911, hearing Bob fighting him out in the kitchen: "Don't bother, honey, I cut the wires. Just leave the scene, OK?"
 * In the original version of Assault On Precinct 13, the gang members cut the phone lines to isolate the station house.
 * Shown on-screen in Bedknobs and Broomsticks. The Nazis cut the phone lines when they invade.
 * At least one phone line is cut in the first Gremlins movie.
 * Michael Myers does this in practically every Halloween movie.
 * In The Return of Michael Myers, Michael doesn't just cut the phone lines of his victim's house. He cuts the phone lines and causes a blackout in the entire town.
 * In Day of the Wolves, the Wolves cut the phone and power lines at the same time they blow the bridge, completely isolating the town of Wellerton.
 * In Panic Room, the thieves cut the main phone lines of the house to prevent Meg and her daughter from calling out, while the phone in the titular room is on a different line but never got connected in the first place, as Meg moved into the house that very day.

Literature

 * In the James Bond novel Diamonds Are Forever, Bond is visiting a mud bath to pay a horse jockey for cheating when it is noticed that the phone line is dead. The novel states that this should have been a warning for Bond, but he did not react and could not when the responsible pair of henchmen came and tortured said jockey for his betrayal.
 * Clock Punk variant in The Fifth Elephant where the equivalent of cutting the phone lines is smashing the semaphore tower and killing the operators.
 * Done in Without Remorse by John Kelly for his final confrontation with the drug ring, which has set up shop in an abandoned warehouse. Kelly cuts the wires and connects his own field phone for a bit of psychological warfare.

Live Action TV

 * Buffy the Vampire Slayer had Ms. Calender cut the phone line when she was possessed.
 * Harpers Island has the killer cutting the phone lines so no one on the island can call the mainland for help.

Theatre

 * In Agatha Christie's The Mousetrap, the murderer cuts the phone wires of the guesthouse where his victims are snowed in.
 * Tom Stoppard's The Real Inspector Hound, a satire which copied most of the twists of The Mousetrap, does the same, although it fails to prevent the phone from ringing again later in the scene after the play reboots.

Real Life

 * In Real Life, Charles Manson's minions cut the phone lines to Sharon Tate's house before killing everone inside.