Short Distance Phone Call

Jayne: [over radio] Cap'n, cap'n, can you hear me?
Mal: I'm standing right here.
Jayne: You're coming through loud and clear.

Mal: 'Cause I'm standing right here.

—from the pilot episode, Firefly

A situation (usually) played for comedy in which two people are talking on the phone, yet are within reasonable speaking distance of each other, sometimes even standing right next to each other. Often times, they are fully aware of this, and for reasons unknown, continue talking via phone anyway.

Increasingly common Truth in Television since the advent of cellphones. For the non-comedic, creepy variant, see The Calls Are Coming From Inside the House and I Can See You.

Examples of Short Distance Phone Call include:

Advertising

A Consumer Cellular ad played with this trope with the McCann Twins.

Anime and Manga

In an episode of Death Note, Light attempts to call Misa's cell phone. Unbeknownst to him, L, who is just a few feet away, had picked her pocket and stolen it. They hold a short conversation before a plot twist quickly throws the show back into serious mode.

Comic Books

In a Gaston Lagaffe strip, Fantasio takes what he thinks is a call from the managers of the company in the next building. In fact the phone is out of order, and he doesn't realize they're actually talking to him through a gaping hole in the wall.
Legion of Super-Heroes: Early in the "threeboot" version, two of the adults discuss the young rebels over teleconference—and are then revealed to be sitting back to back. It's meant to symbolize how isolated from each other the human society has become.

Film

In Airplane! II: The Sequel, Buck Murdock is shown on a viewscreen, talking to one of his subordinates. Then a door slides open, revealing that the viewscreen was a window in the door and Murdock was standing on the other side.
Clueless did this, to show how bloody spoiled the main characters are that they talk on cell instead of walking down the hallway (of course, it was made before cell phones became ubiquitous). They only hang up when they collide.
In Drake and Josh Go Hollywood, after the boys realize they had put their sister on the wrong plane, they attempt to call her. It's just now that they discover that they had forgotten to give her her cell phone, as as soon as Drake finishes dialing the number, the phone begins ringing in Josh's pocket, who is standing right next to Drake, and proceeds to answer the phone. Drake yells at Josh over the phone and then rudely hangs up.
A scene in Kangaroo Jack features the protagonists heading to the telephone at the back of a bar so they can call the number for a pilot they need to hire. Turns out the pilot is the drunk that had just passed out nearby, and to drive the point home, while one protagonist stands idle at the phone, the other one answers the drunk's phone and they begin to discuss their predicament.
In On The Avenue (1937), a broadway show lampooning the lead has her and her father telephoning each other from opposite ends of an enormous table.
In Spaceballs, this trope is used and extended. President Scroob is videoconferencing with a female officer, and she suggests that he beam over. They beam him over with a transporter failure, beam him back to repair the error, then he says he's had enough and he'll just walk. He then walks into the next room where they are waiting for him.

"I'm having trouble with the radar, sir."

In Tremors 3, Burt Gummer and the tour-guide have an angry conversation while Burt is driving. When Burt arrives and parks, he is perhaps ten feet from the tour-guide, yet they continue talking on the phone. At least until Burt hangs up and delivers to the guide's face that classic line "Is your head up your ass for the warmth?".
This occurs in WALL-E, where two of the Denizens of the Axiom are videoconferencing in their hoverchairs... Right next to each other. It serves to emphasize how everyone on the ship is dependent on their gadgets to the point of being unaware of what's going on around them.
In WarGames, Dr. McKittrick and General Beringer are talking to each other on the phone. McKittrick puts down the phone and walks over to talk to Beringer directly—they were both in the War Room, about 20 yards apart.
Parodied in Don't Be a Menace to South Central While Drinking Your Juice in the Hood. Two guys page each other, and then have a phone conversation even though they're standing next to each other.
Used in a non-comic context in North by Northwest where Eve and Leonard discuss plans in two adjoining phone booths.
Help!: Mad Scientist Foot and his flunky Algernon are rigging up an exploding curling stone; Algernon describes his progress on a headset to Foot, who is standing right beside him.
Richie Rich: While eating dinner, Richie's mother calls Richie (sitting on the other side of the long dining table) over the phone if he wants to dine with the parents. It makes sense to maintain indoor voice.

Literature

Discworld: A Clock Punk variant; following the rise of the semaphore network, Vimes laments the sight of people signalling each other from across a room. In The Fifth Elephant Colon demonstrates the new technology by sending a message to the main Watch tower, which is eventually noticed by two officers on the other side of the street, who amble over to see what he wants.

Colon: See? In the old days I'd have had to blow my whistle!

Live-Action TV

I Love Lucy likely invented this with how often Lucy and Ethel would do this.
In season three of Angel, ridiculously adorable lovebirds Fred and Gunn often talk to each other on cellphones, only hanging up when they're in the same room. The idea being that they were too enamored to wait five minutes, of course.
In one episode of Corner Gas Oscar steals the new wireless phone from Corner Gas and uses it as a cell phone. When he gets home, Emma asks "What is that?" Oscar calls Emma on the phone to explain, despite her being one foot away from him.
A variation in Dead Like Me, when George's boss insists that they use email to communicate even though they're sitting at opposite desks so close to each other they probably couldn't both push their chairs back at the same time. And insists it be used for everything. She quits after about two minutes of this.
Happened in the pilot of Firefly with a walkie-talkie device. It's not clear whether Jayne is that stupid (thinking the device is working when he's only hearing Mal's original voice through a few feet of air) or Mal is yanking his chain. Or, he was trying to test the walkie-talkie.
Frasier had this when Frasier and his father were trying to get hold of Niles, because Niles had left his phone at Frasier's place. Martin tried calling Niles from the kitchen, and Frasier picked up the phone, then they had a conversation without even realizing who they were talking to.
Played with in an episode of Mathnet: Kate Monday greets her partner George Frankly in person, but he doesn't respond; she uses her desk phone to call him, and he answers. She greets him again, he looks from the phone to her, she says "It's better not to ask" and they both hang up and continue the conversation normally.
Used a few times on Minty.
In Saved by the Bell, Zack called Mr. Carossi about a car that he wants to purchase - and they both happened to be in the same room. Initially, the two don't realize that they're talking to each other—which led to a variant of Right in Front of Me.
Glee there is a minor example, it was a group call, but started with Tina and Mercedes... and they are walking side by side in a corridor.
The final episode of Will and Grace pulls this one. One scene has Karen talking with Jack over the phone while both are taking a bath. It's soon revealed they're in the same tub.
One episode of Two and A Half Men has Charlie call Rose while the former is a passenger in a car. After a brief conversation, Charlie asks if he can come by to pick her up. We hear a car horn and Rose pulls up alongside him.
A variation with walkie-talkies on Night Court: After newly diabetic Roz takes too much insulin, she goes off and gets lost. Bull finds some walkie-talkies to help with a search. At one point, Harry receives a call from Bull, but it's too quiet. He asks Bull to speak up and we see that they're in the same crowded room.
After being eliminated from The Biggest Loser, one contestant surprised his wife this way.
In one episode of Only Fools and Horses Rodney, applying for a job he's seen advertised in the paper, unknowingly calls Del's mobile (because Del advertised for someone to do Rodney's job when Rodney wanted out). Del, in the kitchen, puts on a silly voice and strings him along for a bit.
Home Improvement: Tim and Jill are on the same line talking to Al, but after Al hangs up they continue talking over the phones. They continue oblivious until Randy enters the scene and gives a WTF? look that Tim notices.
In an advertisement for Dell computers, a mother is in a Skype conversation with her college-age daughter. The mother is carrying her Dell laptop around to show the daughter the house decorated for Christmas. Upon opening the front door, she finds the daughter is standing outside with her own Dell laptop, unexpectedly having arrived at home for Christmas.
In on episode of Kenan and Kel Kenan gets out of listening to Kel's rambling monologue by calling Kel on his cell phone.
Benson is at home in one episode when he gets a call from the Governor. Benson gives him permission to come over for a visit. What he doesn't know is that the Governor is actually calling from his limo in the driveway. The Governor shows up at his door within a minute and Benson asks him "What did you do? Beam over?
A variation is used on an episode of Royal Pains. Evan and Divya are both using laptops on the patio and Evan sends her an email. When she points out he could just get up and talk to her, he says he needs her response for official records.
Castiel's use of Offscreen Teleportation leads to this in Supernatural.

Dean: Yeah, room 31C, basement level, St. James Medical Centre - (sees Castiel right in front of him)
Castiel: I'm there now.
Dean: Yeah, I get that.
Castiel: I'm gonna hang up...now.

Desperate Housewives has one when Lynette follows Tom to where she believes he is having an affair. This leads to an amusing moment when a car alarm is accidentally set off while the two are on the phone.
NCIS:

Gibbs: Call me when you find something, Abbs. *answers phone* Yeah, Gibbs.
Abby: Found something!

In one episode of Soap Burt received a call on his office phone, only to realise that it was from his stepson and business partner Danny, who was sitting at the next desk. After Danny hung up, Burt called him back just so he could slam down the receiver.

Theatre

Dutch cabarettista Javier Guzman invokes this trope when describing the typical behaviour of a city guard. One city guard unsuccesfully tries to communicate with his co-worker through portophone. When the co-worker doesn't respond, the first guard shakes him by the shoulder to get his attention. Turns out he had to press the little button for the portophone to work.
Justified in Rent. Collins called from a payphone to ask Roger and Mark to throw him the keys so he could come up and talk to them.
In Mary, Mary Bob (in the living room) calls Mary (in the bedroom). She comes out to talk to him carrying the phone, then starts to go back into the bedroom to talk via phone.

Video Games

Metal Gear Solid 2: Sons of Liberty did this a lot when characters next to each other engaged in lengthy dialogue, they start talking to each other in person, and then switched to the codec, which in character was supposed to prevent people from listening in on your conversation. It's therefore implied that you think your message out loud for it to be transmitted, and it's explicitly said that the codec directly stimulates the small bones in your ear. The codec screen is just two talking heads and a bit in the middle that shows the frequency, and thus whilst it works for contacting people when you want to, it doesn't make for interesting cutscenes, especially when they get way too long.
The Legend of Zelda Ocarina of Time: Using Saria's Song(which allowed you to talk to her for a reminder of your next objective) right after learning it from her got a semi-peeved comment from her that you could just talk face-to-face.
In Pokémon Gold and Silver and their remakes, you can use your phone to call other trainers. Do this in the same area as them and they usually question why you don't just talk to them in person.
Grand Theft Auto IV makes use of this trope when the player has to find and kill a blackmailer given only a fairly specific area (about fifty yards by fifty yards) and a cell phone number. Realistically, there is an intentional delay between Niko or the blackmailer saying something and the sound of their voice coming from your cell phone.

Web Animation

In an episode of The Strangerhood, where Sam and Wade are talking to each other on the phone, but then Sam points out they live in the same house, at which it's revealed that they were just standing on opposite sides of a wall.

Web Comics

In Megatokyo: Largo, instead of talking, builds a computer from spare parts just to have an instant message conversation with Piro.
- Largo has a more conventional one with Erika a few strips later.
The Sluggy Freelance "Qu atrix" parody, where people are constantly contacting each other one the phone until it's revealed they're actually standing next to each other.
This Wapsi Square strip involves Brandi giggling about having sent Bud an e-mail while they were sitting next to each other.

Web Original

Talies of The Motley Two, in a fit of silliness, begins chatting with Kaogin from two feet away while both are riding an elevator. Kaogin responds by poking him in the ribs intensely.

Western Animation

Variation in Dexter's Laboratory: Dexter calls his arch-rival Mandark to get his help in destroying a bunch of meteors headed towards the Earth. Mandark immediately announces he will solve the crisis himself to get all the glory and leaves...but doesn't hang up, leaving Dexter to stupidly keep saying "Mandark? Hello?" while Mandark takes off in his robot, gets the robot wrecked, stumbles over to Dexter's lab and stands behind him...while he's still on the phone.

Dexter: [to the phone] Hello? I'm talking to you!
Mandark: Alright Dexter. We must work together in the interest of science!
Dexter: [to the phone] Great! Come on over!
[Dexter turns around to find Mandark standing in front of him].
Dexter: That was fast.

In the Dilbert show, Dilbert called Customer Service, and once he got past the computerized options, he discovered that it was the guy in the next cubicle over, who was performing this job for dozens of companies owned by the self-aware computer Compucomp.
On Kim Possible, a fourth season episode finds Dr. Drakken running a successful legitimate start-up company as a front with his business manager, Hank Perkins. Shego walks in on Hank and Drakken to try and get Doc refocused on the secret plan, but they're wearing headsets for a conference call. After a minute Shego realizes that Hank and Drakken are the only ones on said call.
In an episode of Pinky and The Brain, a parody of Bill Gates has his board of directors sit down around a conference table, while holding a webcam teleconference. This was around the time that the first version of NetMeeting was brand new.
The Futurama pilot had Leela call two police officers who were standing a few feet behind her for back-up using her fancy ultra-futuristic wrist communicator. "We'll be there in fifteen minutes!"
An early episode of SpongeBob SquarePants does this in a Split Screen call between Spongebob and Patrick.
A gag in one episode of Sheep in The Big City when talking about 'technology in the Big City' had this exchange:

Guy 1: (Shouting into cell phone:) "Jerry? Jerry, can you hear me!?"
(Pan out to reveal that he's standing back-to-back with another guy with a cell phone)
Jerry (Shouting into phone:) "Barely! There's some guy next to me screaming his head off!

Inverted in Richie Rich, while Richie and his dad are showing a guest around the mansion. Guest wants to say hi to Mom, and Richie picks up a phone. Then he asks for the long-distance operator.
An episode of Jimmy Two-Shoes opened with Jimmy and Beezy were texting and sending funny pictures to each other. When we pan out, they're standing right next to each other.
In the third-to-last episode of the fourth season of Code Lyoko, Aelita gets a phone call from Jeremie, only to find out that a few seconds later that he's right behind her.
A strange example in Rollbots when Spin calls Zilla and Bug in a Split Screen, then the Split Screen vanishes, revealing that the two appeared right behind him.
Johnny Bravo: In "Fugitive Johnny", Johnny calls the police officer who is after him in order to make her an offer. She promptly tells her men to trace the call; they discover he's somewhere in the police depot. The camera pans out, and it turns out Johnny is in the same room as them. Sitting at the same table.

Real Life

This doesn't really work well with cell phones in real life, as (unlike with land lines) there is a noticeable lag between when one person speaks and the other one hears him. If they are close enough for one to physically approach the other, the strange delayed echo caused by the cell transmission would give away the game.
Then again, maybe the reveal in the first few minutes is part of the joke. You're running late, your office calls your mobile while you're standing in their parking lot and asks "Are you coming in today?" to which you respond "I shall be in in a minute" before walking through the door and giving the game away (or, likewise, the repair garage is calling to say your vehicle is ready - when you're right next door and can just walk in while still on the line). Maybe a retail store is calling to say the items you'd backordered just came in... while you're in the store, standing right next to the caller. Bonus points if you're answering this as a Voice-over-IP call and just happen to be on their open wi-fi network at the time.