A character, through recklessness or bad luck, ends up unintentionally using some form of long-range communication in a manner that contacts an evil entity. Typically this results in serious negative consequences, ranging from Mind Rape and Poke in the Third Eye to Demonic Possession. The means of communication through which Mordor is contacted may be magical, such as a Magic Mirror or Crystal Ball, technological, or some form of Psychic Powers. This trope may be a result of a character finding out what that button does by pressing it. Alternatively, The Klutz may cause this by tripping over the Artifact of Doom or dropping something on the Big Red Button. Sometimes, they need only Speak of the Devil to get it on the line.
- In Dragonball Z, the scouters also act as communication devices, and it was due to their function as communicators that Frieza learns about the dragon balls, using them to make a wish, and enables himself to get a head start on Vegeta in going to Namek to use their dragon balls.
- Years later, in the Dragon Ball Super manga, Goku and Vegeta are told of the escaped Galactic Patrol prisoner, Moro. Attempting to get a read on him, Goku searches for his ki; after sensing him, he's shocked when Moro makes it clear that he is also able to detect Goku reading his ki, flashing him a devious grin from lightyears away.
- At the end of Kotoura-san — episode 10, The ESP society sets out to find the criminal (whose crimes include assault, murder, and rape of teenage girls) using Haruka's telepathy. After she gets a very harsh Beam of Enlightenment, Haruka immediately keels over and nearly passes out again because she did not expect the criminal to have such a twisted, distorted, and unnaturally deep mental voice and that said criminal knows that the ESP Society has fallen for the Schmuck Bait. Thankfully, the criminal wasn't targeting Haruka during this incident. This doesn't last. In the next episode, the actual criminal (Detective Aki Tsukino's Enemy Within) deliberately targets Haruka not only because she has friends despite being a monster (Tsukino's main motive derived from jealousy), but also because of the aforementioned telepathy which Haruka showed to both her and Detective Gantestsu Ishiyama earlier in episode 10.
- In I Can't Believe It's Not The Justice League, Booster Gold inadvertently sends the Superbuddies to Hell while fooling around with a mystical artifact.
- In the first issue of The Second Life Of Doctor Mirage, Hwen Mirage accidentally ends up in Master Darque's crosshairs after conducting experiments with necromantic energy, which disrupts Darque's own attempts to summon the energy for his own ends.
- The Self-Insert protagonist of With This Ring doesn't use a Lantern Oath to recharge at first, he just taps the ring against the lantern and says "Recharge." The first time he tries saying an oath that he remembers having read before, though, he sees a vision of Larfleeze's cave and the Ophidian, which freaks him out. He later crosses a Godzilla Threshold and states the full oath deliberately, to summon the Ophidian.
"This is my power-"
The treasures of civilisations, fallen ages past. Bones stripped of flesh and marrow. Vast serpentine eyes-
I yank my hand back, slip, and fall onto the soft carpet.
!Very bad very bad!
I pick myself up.
Did I just see Larfleeze's cave? That can happen?
I guess it's not my power after all.
I open my hand again, and hold it out to the lantern.
Ring, standard recharge this time.
- Inverted for laughs in The LEGO Ninjago Movie where, rather than Lloyd accidentally contacting an evil being in a supernatural way, he is contacted in an entirely mundane way when his Archnemesis Dad Lord Garmadon accidentally dials him on his cell phone. Bonus points in that Garmadon attempts to have a pleasant chat with him rather than doing anything heinous, and for literally butt-dialing "L-Loyd":
Garmadon: Look, I didn't call you. My butt called you. Well, no time to chat. Sorry, Daddy's got to go to work. Gotta get that Green Ninja.
- Guardians of the Galaxy: Drax gets roaringly drunk and drunk dials Ronan the Accuser, daring him to come over and fight. Ronan takes Drax up on the offer.
- In the 2020 horror short film Host, one of the participants in an online seance over Zoom says she's been contacted by the spirit of a boy she once knew who committed suicide, only to later admit she made that up because she was bored. The woman leading the seance warns them this may have summoned a demon, which we later learn it did.
- In Howard the Duck, a group of scientists build some kind of telescope/transporter device, with which they accidentally summon one of the Dark Overlords of the Universe. And Howard.
- In the ARG backstory for TRON: Legacy, Flynn's analog-world supporters band together to send out a communication pulse through the world's computer networks to try and find him. As The Grid is a mostly (but not entirely) isolated system, this pulse give Clu the means to send out a message to Alan's pager, intending to set a trap. In the film itself, Sam Flynn demonstrates he inherited his old man's foresight by looking at the commands for the laser situated right behind him and deciding to press "Yes" when asked if he wants to run the last command entered.
- Animorphs: The Ellimist's species was destroyed because of a misunderstanding. One of their favorite activities was basically super-advanced Civilization-type simulations, and when these were broadcasted into space they were caught by aliens who thought the Ketran played games that ended whole species for fun. Oops.
- In the first book of the The Bartimaeus Trilogy, Nathaniel attempts to spy on his master using a scrying-glass, without the master ever finding out about it. He ends up having the psychic equivalent of a Skype call with him! Thankfully his master gets distracted and the imminent Poke in the Third Eye never happens.
- The Black Magician Trilogy: When the Black Mages Akkarin and Sonea are convicted and exiled, their Wizarding School psychically broadcasts the news nationwide. They get a polite thank-you response from a cabal of heinously powerful enemy Archmages, who promptly invade the country now that they know its best defenders are gone.
- Blindsight: The events of the book turn out to have been set in motion because the aliens came across Earth's radio shell. As the aliens are sapient (capable of rational thinking) but non-sentient (incapable of feeling or perceiving reality subjectively), Earth's transmissions make no sense to them even after they decode the language (after all, if you have no sense of 'self', how do you translate the word "I"?). The aliens are incapable of seeing this as anything but a memetic attack or a monkey trap meant to waste their time, provoking a hostile response.
- The entire plot of Brimstone Angels got kicked off because of this; Havilar tried to use a magical ritual she didn't fully understand to summon an imp she could use as a sparring partner, and unfortunately for her she didn't do the spell very well and got Lorcan, a much more powerful devil who happened to be near the imp, instead. The good news was that Havilar, being content in who she was and the skills she was good at, had absolutely no interest in bargaining for anything Lorcan had to offer. Then her twin sister Farideh walked in...
- In Lords and Ladies, Diamanda thinks the Lancre way of witching is too old-fashioned for her and tries out parodically Wiccan spells instead. While this would normally be doomed to failure, the Queen of the Elves caught her mind and made her open the way for their invasion in exchange for power.
- Parodied and subverted in Going Postal with a Shout-Out to The Lord of the Rings when wizards trying to get a long-distance call through the Omniscope see an enormous fiery eye. It turns out it's the person whom they're trying to contact, he's just zoomed too close and his eye's inflamed.
- In For We Are Many, this is how the Others become aware of Bill's base in Epsilon Eridani (he's been periodically sending high-powered transmissions to the other Bobs, unaware of the existence of the Others).
- Gentleman Bastard: The Bondsmagi know that the Eldren Precursors (a) used incredibly advanced magic liberally and (b) abruptly went extinct, and their leading theory is that the magic attracted the attention of something terrible from beyond the stars. The Bondsmagi's entire organization is based around dispersing their magic use to avoid courting the same fate.
- Harry Potter:
- In Harry Potter and the Chamber of Secrets, a variant of this occurs with Ginny and the magic diary of Tom Riddle that Lucius Malfoy slips into her bag. She writes into the diary many things that happened in the school, allowing Riddle to get info about Harry Potter, and he slowly possesses her body to give himself a more corporeal form.
- In Harry Potter and the Order of the Phoenix, Harry starts getting unintentional visions of Voldemort's doings through their Psychic Link, which he uses to save Mr Weasley at one point. Dumbledore has Harry train in Occlumency to stop this happening, but Harry thinks the visions are useful, so doesn't put much effort into the lessons, resulting in Voldemort being able to use the link to set a trap for Harry.
- The Lord of the Rings:
- Pippin tries to use the Palantír and unintentionally ends up getting face time with Sauron himself. Sauron stole one of the Palantíri long ago, so anyone who tries to use one of the others risks an audience with Sauron if his attention happens to be on his Palantír at the time (and it always is) — although Unfinished Tales makes this more a matter of chance by explaining that contact can only happen if the user is facing the direction of the other Palantír. Denethor, Steward of Gondor and Boromir's father, has been using the Palantír at Minas Tirith for years, and Sauron has used this to whittle away at his mind. This isn't explained in the movie, making it look like his madness stems solely from grief over Boromir's death.
- The Fellowship Of The Ring. Frodo sits on the hill Amon Hen while wearing the One Ring, which allows him to see vast distances. Unfortunately he looks at Mordor, which allows Sauron to detect him and start searching for him. Luckily Frodo gets a telepathic warning from Gandalf (who's supposedly dead at the time) and takes off the Ring just before Sauron reaches him. In the film, Sauron looks directly at Frodo and tells him he can't hide from him.
- Angel: As seen in a flashback, Fred accidentally opened a portal to Plrtz Glrb when she read an ancient text aloud, not knowing the language. Turns out this wasn't an accident.
- Are You Afraid of the Dark?: A character hears an urban legend about a guy named Billy Baxter who was imprisoned by "The Phone Police," a secret group who punishes people who make prank phone calls. He looks up Billy Baxter in the phone book and calls him for a joke. Once he does this, the Phone Police start targeting him.
- Buffy the Vampire Slayer:
- In "I Robot, You Jane", Willow accidentally releases the demon Moloch when she scans the book he is trapped in into a computer.
- In "Fear Itself" a bunch of fratboys paint a summoning circle on the floor thinking it's just a cool design that'll look good for the Halloween party. When Oz cuts his finger and drops blood on the design it accidentally activates the circle and causes the frathouse to become possessed by Gachnar the fear demon.
- In "Once More, With Feeling" Xander brings the singing demon Sweet to Sunnydale through a talisman. Thought that it was just a spell to bring "dances and songs," not realizing that Sweet would kill people.
- Game of Thrones:
- Inverted, where illiterate villain Amory Lorch tries to send a letter containing the Lannisters' plans for moving forward to his ally, Lord Damon Marbrand, accidentally sends the letter to one of the Starks' vassals, Lord Marlin Dormund.
- Bran does this, with disastrous consequences, in season 6. While warging without the aid of the Three-Eyed Raven, he sees the Night King, who is able to mark Bran and render the tree vulnerable to invasion from the White Walker army.
- Stranger Things: Eleven, while using her psychic powers to eavesdrop on a Russian official, accidentally contacts the Demogorgon, which then proceeds to open a rift between our world and the Upside-Down.
- In The Twilight Zone (1985), a mathematics professor gets frustrated with some cutting-edge equation and declares that he'd sell his soul for the answer in "I of Newton". A demon appears and is prepared to deliver, service (actually negotiable) for goods (locked-in) and the rest is about the professor trying to talk his way out.
- Changeling: The Lost: Changelings can have telephones in their Player Headquarters in the Hedge, the Eldritch Location "between" the mundane world and the Land of Faerie. However, they come with the risk that a dreaded True Fae will pick up the call instead of the intended recipient.
"Ah... there you are."
- Shifters in Rifts have the (optional) ability to gain additional power by seeking the favor of a more powerful being. They can do this by creating a tiny Rift and seeking a creature to make contact with. Where this trope enters in is that the Communication Rift is basically random; there's no telling what the Shifter will make contact with. Often, the Shifter will unwittingly make contact with an Eldritch Abomination (sometimes pretending it's a god of light or similar), and enter into a pact with it, unaware he's making a Deal with the Devil until it's too late.
- In the various Warhammer properties (Warhammer, Warhammer 40,000, et al), this is a constant danger for any wizard or psyker — All magic is drawn from a hellish immaterial realm ruled by Eldritch Abominations, and any careless power use can draw the attention of daemons and other nasty creatures out to kill, possess or make costly bargains with the hapless caster.
- Some daemons of the God Tzeentch in particular are known for answering botched summons meant for other daemons, often to screw over the summoner just to undermine the minions of other Chaos Gods. One being in particular, the Changeling, is known for his nature as a prankster extraordinaire. Sometimes his pranks are genuinely funny (from an outside point of view), sometimes they end with entire populations being put to the sword.
- In Marlowe's play Doctor Faustus, though Faustus himself knows exactly what he's getting into when he starts summoning demons, Those Two Guys that serve him don't. They're larking around, mimicking Faustus's incantations more as a joke than anything else, and end up summoning Mephistopheles himself. Needless to say, he's not happy at all and they get transfigured into animals.
- Baldur's Gate II: Throne of Bhaal introduces the Wild Mage class, whose spells had a small chance to have their effects randomized via wild surge. One possible effect is to accidentally summon a demon, which could be bad news for anyone nearby who isn't under the effects of Protection from Evil.
- In Fallout 2, there is a computer in the Gecko power plant that you can use to contact the Enclave, the game's Big Bad organisation. You have an option of insulting the soldier you're talking to in a number of ways, and if you do, they will send a squadron of Power Armor-wearing soldiers after you. You will encounter them later in a special encounter, and unless you're high level by that point, or unless you have a high enough Speech skill, it's not going to be pretty.
- In Mario Party 3, you can buy a Bowser Phone from Koopa Kid's item shops that instantly calls him to deliver misery. When you dial him, he asks who is calling. You can lie and say whoever you want. You can also be honest. The final option is "Who do you think?", which yields a random result. Woe unto you if you choose the last option and Bowser guesses correctly.
- Unless of course you have zero coins, in which case Bowser will give you money instead. It would still be a better move to just specify yourself in that case though.
- The second level of Medal of Honor: Rising Sun has you manning the AA gun of a PT boat during the Attack on Pearl Harbor. Near the halfway point, the boat takes damage from a bomb exploding, which causes the radio to go on the fritz and for a moment it picks up Japanese radio chatter.
- In NetHack, the Big Bad Wizard of Yendor lives in an isolated tower in the middle of a dungeon level, which can normally only be reached by going down through the outskirts of that level, to a lower level which contains a magic portal to the tower. If you have a telepathic pet, the pet may helpfully wake the Wizard with a ranged psychic attack when you first cross his level, which can draw him out before you're ready to fight him.
- Starcraft: When Zeratul kills a Cerebrate for good (normally impossible, but the Dark Templar's blades are able to prevent the Cerebrate from being reformed in the Overmind), his mind is briefly linked with the Overmind, allowing it to learn Aiur's location and launch an invasion that is only repelled several years (and expansions) later.
- In The Witcher 3, agreeing to have some drunken time will lead to phoning Heirach Hemmelfart, the head of the dominant religion in the North and the man who all the witch-hunters (theoretically) answer to, while he's on the crapper. Hilariously enough, he's of the opinion that it's Mordor that's calling him because he thinks the witchers in drag are the Lodge of Sorceresses coming to get him.
- World of Warcraft reveals that the cause of the Eredar joining with the Burning Legion and a small splinter faction becoming the Draenei was because one of their master summoners continually sought greater and more interesting things to bring to Argus from across the universe... and managed to call Sargeras, who taught him how to summon demons and the power of fel magic. The summoner went on to show off his new "pets", was told to never do it again, decided to create an army of demons to take the world for his own, and was defeated because his favored student informed the leaders of the Eredar. The reason this isn't a happy ending? Said pupil was Archimonde, who wanted the summoner's position for his own, and was just as enthralled by fel; he just hid it better until Sargeras came to their world personally.
- Psionically ascended empires in Stellaris can reach into the Shroud every ten years to receive random temporary (de)buffs (or nothing at all). One of these events has your psykers accidentally come across the minds of the ruling conclave of a nearby Fallen Empire. If you decide to try and invade their minds, you can potentially gain access to a random piece of top-tier technology, but there's also a good chance that the guys notice the intrusion and slap you with a hefty relationship drop that may result in a Hopeless War for your empire. The game allows you to hang up on Mordor at any time, though, so anything bad that happens is entirely your own fault.
- Target Earth: Later in the game, Rex is given a communicator that can listen and broadcast on Chron communications. He forgets the broadcast part, and his loud exclamation of surprise when it starts tuning in to enemy messages alerts them he's listening, and allows for The Dragon Rance to start directly addressing Rex.
- In Darths & Droids, Luke accidentally summons an avatar of Darth Vader while on Dagobah, informing Vader that Yoda is alive and training Luke on an unknown swamp planet and leading into the rest of the campaign's plot.
- Satan and Me is about a girl who accidentally summons Satan due to sigils printed onto a menstrual pad.
- Parodied in this xkcd. A protester screams "WAKE UP SHEEPLE!", only to accidentally summon actual sheeple, which are horrifying underworld sheep-men monsters.
- Before Critical Role began streaming, Vox Machina broke into the house of a blue dragon disguised as a council member of the city they protect and, after being transported to his lair and defeating him, saw four obsidian orbs embedded in the wall of the cave. One of the party members touches one of the balls, which causes it to alight with an draconic eye and say "Intruders... I know your face now. [Brimscythe] is a fool, and so are you, insect," and the orbs all crack. MUCH later during the stream, it turns out the this eye belongs to a member of the Chroma Conclave, an alliance of ancient chromatic dragons that desire to control the entire continent.
- The Grim Adventures of Billy & Mandy: One episode involves Billy somehow getting Cthulhu via a prank call. Cthulhu immediately hires Billy and Irwin to start calling everyone in Endsville, mutating the citizens into Starfish Aliens. Like everything else on this show, the horror is very much played for laughs.
- The Powerpuff Girls: In Telephonies, the Gangreen Gang trick the mayor into leaving his office and subsequently abuse the hotline phone, siccing the girls on Mojo Jojo, Fuzzy Lumpkins, and (most lethally) Him for shits and giggles, despite none of them doing anything evil that particular day. Once the three villains figure out who's really to blame, the results are predictable. A rare case where the butt-dialer intended to make the call and knew the entity on the other end was dangerous and supernatural, but simply didn't consider the consequences.
- Futurama: Inverted in Godfellas, where Bender, after floating in space for days, encounters a galaxy beeping to itself in binary code. Attempting to communicate reveals that the galaxy is actually God. Or similar.
- My Little Pony: Friendship Is Magic: The Cutie Mark Crusaders have a quick fight in front of a mysterious statue during the Season Two Premier episode. Naturally, the statue is the can for Discord, and (being an implied Emotion Eater), a little bit of random derision in his proximity was all he needed to escape...
- Some people have expressed concerns about the radio transmissions our civilization has been sending out into space over the past century or so, saying they could inadvertently attract the attention of powerful and hostile/indifferent aliens. Deliberate transmissions (such as the Arecibo Message) and physical artifacts (such as the pulsar maps on the Voyager spacecraft) have also caused worry. This often ignores the fact that it's going to be tens of thousands of years before any physical craft in existence passes near anything of note and radio signals will attenuate to virtual nothingness after only a few dozen light years. Moreover, over the last several decades, the signal strength of our regular transmissions has decreased, as we have moved away from a few powerful transmitters to many less powerful ones.
- On an intersection between "Real Life" and "Religion and Mythology" lie people who actually do believe that yes, doing something that's not Christian enough for them is literally this trope for real. What counts as "not Christian enough" could be yoga, rock music, fantasy fiction, tabletop RPGs, Eastern martial arts, vegetarianism... Yep, whenever you hear about Moral Guardians railing about these sorts of stuff, chances are at least some of them are motivated by a literal belief in this trope in action.
- The legend behind the "NORAD Tracks Santa" program is that for Christmas 1955, a Sears store in Colorado Springs printed an ad that said children could call a special number to have Santa Claus' progress around the world relayed to them. But due to a misprint, the children ended up accidentally calling the Continental Air Defense Command instead. Supposedly the senior watch officer decided to just roll with it and now it's an annual tradition.