This trope occurs when someone's attempt to communicate with a character ends up compromising them. Unlike other times when this happens, this is almost completely out of the character's control. Most of the time, it's not even malicious; the person calling just has no idea what situation the character is in when they make the call.
This most commonly occurs when a character is sneaking through enemy territory and someone on their side calling them or breaking radio silence reveals the character's presence. Note that the character needs to be aware that they have been discovered for this trope to apply.
Subtrope of So Much for Stealth. May overlap with Embarrassing Ringtone. Compare Kinda Busy Here when a call becomes inconvenient not because the callee's cover is blown but because they are busy with something else more important, which is usually played for laughs. If someone is trying to assure others that things are a certain way and a call soon afterwards says otherwise, they are Instantly Proven Wrong.
- When vibrate functions were a new feature for cell phones, a cell phone commercial featured a spy who gets her cover blown by the cell phone spokesperson, who's calling to tell her about how having a cell phone with vibrate is better than one without.
- Episode 1 of Code Geass has Lelouch trying to sneak his way out of a massacre where his long lost best friend was just shot for refusing orders to kill him for knowing too much. Unfortunately for him, Shirley, who is at school, calls his cell phone in hopes of reaching him, alerting the soldiers to his location, resulting in him almost getting executed.
- In Arthur Christmas, after crash landing Santa's sleigh in the Serengeti, Arthur manages to put a pride of lions to sleep by waving his musical slippers and singing. Afterward, the north pole tries to communicate with them via the sleigh. The resulting noise wakes the lions, leading Arthur and company to make a hasty escape.
- In The Incredibles, Helen, in order to find out where her husband is, activates the homing beacon on Mr. Incredible's suit while he is infiltrating Syndrome's base. This activates the base's defenses which results in his capture.
- In Zootopia, while Judy and Nick are sneaking around the facility housing the mammals that had "gone savage," Judy's parent's try to call her on her phone. The sound alerts the head doctor who calls security, forcing Judy and Nick to hightail it out of there.
- In Die Hard 2, the conveniences of the 90's conspire against McClane, as Holly calls his pager from a skyphone. The first time is harmless, as McClane is just waiting at the airport, but the second time, after the plot's in high gear, it's far more hazardous. That time, McClane is trying to sneak towards the church that the terrorists are using as a base, and the pager alerts the guard.
- In Sneakers, Martin is using an Air-Vent Passageway inside an enemy-controlled building. A guard is moving along a corridor under him while searching for him. Martin's partner Crease calls him on his radio, making enough noise that the guard hears it and Martin's location is revealed. The guard starts shooting into the ceiling with his shotgun to try to kill him.
- Subverted in A Walk Among the Tombstones. After the cemetery shootout, Scudder realises his Tagalong Kid is missing and calls his mobile, not realising he's hiding in the back of the serial killers' van. Fortunately they've arrived at their destination by the time the call is made; one hears the ringtone, but dismisses it as coming from a nearby house.
- In DEBS, Lucy Diamond is moving along an Air-Vent Passageway in the ceiling while her nemesis Bobby is following her in the corridor below. Suddenly Bobby's radio squawks, alerting Lucy to the fact that she's been detected and allowing her to escape.
- The French movie Rosalie Blum is about a sympathetically portrayed Stalker Without a Crush who starts regularly following a woman (the titular Rosalie) around because he's convinced to have met her before but can't quite place her. Rosalie is part of a church chorus and the protagonist forgets to turn off his phone while entering the church. His My Beloved Smother chooses that moment to call him.
- In The Terminator, this is inverted. Sarah is the one in danger, and tries to call her friend Ginger to warn her of the killer that's stalking her. Unfortunately for Sarah, Ginger is already dead and the voice mail Sarah leaves lets the Terminator not only know it killed the wrong woman, but exactly where Sarah is.
- In World War Z, the protagonist's wife calls while he and his team are trying to quietly sneak through a horde of zombies. The call alerts the zombies and results in some deaths.
- Spider-Man: Homecoming: Peter is trying to spy on Toomes' dealers Brice and Schultz selling alien weaponry to Aaron Davis, when his position is inadvertently given away by the sound of his phone ringing as Ned tries to call him.
- In T2 Trainspotting, as Renton tries to hide from Begbie in a car park, his iPhone's ringtone gives him away when Simon calls him to ask where he is.
- Discussed then Averted in The Thrawn Trilogy. Han goes off to follow a suspicious looking character, leaving Lando and Luke on their own. Han tells Lando not to call him, as he might be somewhere he wouldn't want a callbeep going off. Lando later tries to comm Han anyway, since there's an Imperial raid happening, but it's moot because the Empire is jamming comm traffic and Han had his comlink taken by the suspicious-looking character's associates anyway.
- In Agent Carter, while Peggy is investigating the Roxxon factory, Mr. Jarvis calls her on his walkie-talkie. This alerts the workers to her presence, which ultimately leads to a truck of Nitramine escaping and to the implosion of the factory.
- Has happened at least once on Chuck, when Chuck's Locked Out of the Loop best friend Morgan Grimes calls his cell phone, alerting his enemies to his location.
- In Black Mirror: Playtest, this is subverted and then played straight. The protagonist of the episode tries to take a sneaky photograph of the new gaming device he's testing with his phone, and his mother calls when the technician comes back which raises the suspicions of the technician (who confiscated the phone and turned it off before the test) but she merely dismisses it and carries on with the experiment. Only at the end do we find that the events of the whole episode were in fact just a Dying Dream in the protagonist's head, as the ill-timed call in real life caused the device to malfunction and fry his brain.
- Subverted in the first episode of How to Get Away with Murder. In one of the flash-forwards, Wes, Connor, Michaela and Laurel are hauling Sam's corpse into the woods when Laurel gets a call from Frank. A nearby couple hear her phone ringing and decide to leave instead of investigating further.
- In Frequency, when Raimy sneaks into the killer's house on her own, her phone starts ringing which alerts the villain and eventually leads to his escape.
- In one episode of NCIS: Los Angeles the team rescues a group of kidnapped Marines from a group of mercenaries, then is led to their employer through one of their cell phones.
- On an episode of It Takes a Thief (2005), Jon is robbing a sorority and decides to wait until all the residents are home (presumably so he doesn't have to worry about anyone showing up while the heist is in progress). Jon makes his move while all the girls are in the living room, assuming they'd all be there for a while. Instead, the girls almost immediately split into small groups and meander about. Matt, watching the cameras decides to call Jon to warn him. The trope ends up subverted when it turns out Jon turned his phone off prior to beginning the heist.
- A crowning moment at the end of Sherlock's episode "A Scandal in Belgravia". Irene texts Sherlock to say goodbye as she is about to be executed. A few seconds later she hears the text message tone she put on his phone for her number. This makes her realize he is with her in the room. Cue a Big Damn Heroes moment as Sherlock blows his cover and frees Irene from her captors.
- CSI: Played for Drama during an episode following the investigation of an undercover cop that was infiltrating a criminal biker gang and had been beaten and stabbed to death by them. It turned out that his wife had gotten drunk and, believing that he was having an affair for some time already, called a number that he had on speed-dial (which was the gang's hangout) and blurted out his real identity to the waitress (who she thought was the officer's mistress)... and to make things worse, the officer was right inside the bar when she did this. After a whole episode of being devastated because of her husband's death, she utterly collapsed when Brass told her this and then arrested her.
- Bionic Woman. While the title character is hiding from well-armed mooks in "Paradise Lost", her Bratty Half-Pint sister rings demanding to know where her Tenacious D T-shirt is.
- Blake's 7. As their teleport bracelets also serve as Comm Links our heroes can't afford to turn them off, so this trope happens a couple of times when hiding from patrolling Federation troops.
- Father Ted. A recurring gag has Ted often call a friend, fellow Priest Larry Duff, for advice. Every time his cellphone ringing results in disaster for Larry. In one example he is strapped to a wheel on a stage while a blindfold magician is throwing knives at him, having called for complete silence.
- Daredevil (2015): While James Wesley is in the midst of trying to intimidate Karen Page, his phone suddenly rings as Wilson Fisk tries to call him from the hospital. The brief amount of time that Wesley looks down at the phone is just long enough that Karen is able to grab Wesley's gun and shoot him to death.
- The Defenders (2017): The sound of Claire's phone ringing tells Bakuto that someone is hiding nearby, but he's too busy intimidating Colleen to do anything about it.
- On Archer, a ridiculous number of ISIS' undercover agents have had their covers blown because Sterling Archer got drunk and happened to call them while they were on a mission.
- In Batman: Mask of the Phantasm, the Joker has paid Councilman Arthur Reeves a visit. During this time, Andrea Beaumant—the daughter of the man they're discussing—calls, and the Joker—immediately suspicious—forces Arthur to pretend that all is well. Afterwards, the Joker comments on this:
The Joker: "Now ain't that a co-inkidink. We're discussing the old man and the spawn of his loins just happens to call. Makes you wanna laugh..."The next scene is Reeves in a fit of laughter in the hospital.