Why Does My Voice Sound Like a Robot on Phone Calls?

A story of radios, ones and zeros, and little computers trying to make our calls sound clearer

A GIF of an illustrated robot talking on a cell phone. Illustration: Lacey Browne/Consumer Reports

Every day, innocent people get on the phone and find themselves transformed into a robot by an evil system of telecom infrastructure.

At least, that’s what it sounds like on the other end of the line. It happened a few months ago when I was on the phone with my Dad. In the middle of our call, something weird happened. “Yikes, you sound all distorted and metallic," he said. After a minute we hung up.

I’m not alone. “I have an iPhone 11 and keep getting complaints that I sound like a robot,” one Apple customer wrote on the company’s online forum. I found hundreds of iPhone and Android users complaining about similar problems.

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When I set out to investigate, I didn’t turn up evidence of an encroaching cyborg army. Instead, I learned that the robot-voice phenomenon is the result of benevolent technologies trying to prevent interrupted phone calls.

“When information is going over a digital network, it has to be converted to bits,” says Alex Hills, a professor of engineering and public policy at Carnegie Mellon University. In other words, data is translated into ones and zeros that can be understood by a computer. That’s true no matter the content: texts, emails, your voice on a phone call, you name it.

Your phone transmits those bits through the air as radio waves. “At the other end, the receiver converts the ones and zeros back to the original information,” Hills says. “That’s how digital works.”

But things can go wrong. Problems can crop up when the voice data is being converted from one format to another, but often it’s just interference during wireless transmission, like competing radio traffic or physical objects standing in the way.

Sometimes the call drops. Other times the signal is strong enough to maintain a connection, but part of the information the radio waves are transmitting gets corrupted—ones get flipped to zeros, or strings of bits are lost altogether. It’s the digital equivalent of the snow or noise you’d hear on an old AM radio.

The solution starts with what’s called error detection. “The receiver knows it has this stream of bits, and it has an error detection system that can tell there are little bursts of bits coming through that aren’t right,” Hills says.

It’s a scenario he knows well from the time he spent in the early 1990s building the world’s first big WiFi network. WiFi also transmits data using radio frequencies. He described the effort in a book called “WiFi and the Bad Boys of Radio.” “We used a lot of that technology,” Hills says.

The errors can be relatively simple to deal with when the information is something like a text, an email, or the words and photos on a webpage. The system just asks the sender to transmit another copy of the data. But the fix is a lot more complicated with real-time, continuous streams of information like phone calls.

Your cell phone and other telecommunication systems also use error detection, “but with voice calls you don’t have the luxury of retransmission,” says Sanjay Udani, a technologist at Verizon who was one of the lead architects of the company’s FIOS network. With a call, “you can’t resend the packets because there are just milliseconds of delay,” and there’s no backup copy of your voice. 

Your phone could just play silence for the parts of the call where the information isn’t coming through correctly, but that would be hard to understand. So instead, the system tries to correct the error, guessing at what those missing bits might be and generating sound to fill the gaps in the middle of your words. “Sometimes it does a great job, but sometimes it can sound robotic or distorted,” Udani says.

Essentially, the distorted voice you’re hearing is the result of a bunch of little computers involved with your phone call, trying their best to chime in and help you get your message across.

The robot voice problem can happen to anyone, from time to time. But if it comes up frequently, engineers have a few suggestions.

How to Fix Your Robot Voice Problem

There are a few things you can try. If it’s an issue that’s bothering you on one particular call, the easiest fix is to hang up and dial again. “That’s like rebooting—it can create a different path,” for the data, Udani says. If that doesn’t cut it, try moving to a different location, or ask the person on the other end of the line to do so.

It’s a different story if the robot voice is cropping up all the time. That could mean there’s an issue with your device, rather than something going wrong with the signal along the way.

First, try turning off your phone’s WiFi calling feature, which routes your calls over WiFi instead of cellular networks. That feature can help save money by cutting your data usage, but there’s a downside: If you’re in the middle of a call being sent over the internet, and there’s suddenly a bunch of competing traffic from someone streaming a movie, for example, the call can get messed up.

On the other hand, if you’ve got poor cellphone reception at home, it might help to turn on WiFi calling. It’s worth a try. You can find instructions online for how to control WiFi calling for both iPhone and Android devices.

Still having trouble? There could be an issue with your phone’s codecs—the computer programs that convert signals from one format to another. Apple and Google’s PR departments didn’t get back to me when I asked them about this problem. But in an answer to a question posted on Apple’s site last year, a company representative recommended updating your device’s software and carrier settings, and restoring your phone’s default network settings

Android users can do the same for their phone’s software, reset their network settings, and update their carrier services

As a last resort, you can try a factory reset of your device—instructions are easy to find online. Just back up your data first.

If none of that works, ask yourself if the robot voice only crops up when you’re using headphones, because all these same issues could have to do with a Bluetooth problem. Try using a different pair, and do a little Googling to see if there’s a firmware update for the headphones you’re using.

When all else fails, the problem may lie with your cell service provider. You may want to try getting in contact with them. They might be able to help, and at the very least it’s worth alerting the company in case there’s some broader problem happening in your area. It will help to be prepared for some of questions they might ask. Try and figure out when and under what circumstances the robot voice problem happens. However, the solution could come down to picking a different service provider that has better coverage where you live.

It’s also worth keeping in mind that not all sound distortions can be traced to data corruption. If you’re having consistent audio problems, check to see whether there’s dirt or lint on your phone’s microphone, or if you’re the one hearing the distortions from people you’re talking to, take a look at your phone’s speaker. (Cleaning it incorrectly could cause damage, so you may want to ask a repair professional.)

And, finally, while I didn’t uncover a cyber-army invasion, anything is possible: If you see something, say something.

Headshot image of Electronics editor Thomas Germain

Thomas Germain

I want to live in a world where consumers take advantage of technology, not the other way around. Access to reliable information is the way to make that happen, and that's why I spend my time chasing it down. When I'm off the clock, you can find me working my way through an ever-growing list of podcasts. Got a tip? Drop me an email ( thomas.germain@consumer.org) or follow me on Twitter ( @ThomasGermain) for my contact info on Signal.