During a phone call, one person can hear the other, but the other cannot. Why is this?
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Modern phone calls feel instantaneous and effortless, so when audio suddenly works in only one direction, it can be surprisingly frustrating. You may hear the other person clearly, respond naturally, and assume the conversation is flowing—only to realize they hear nothing from you. This “one-way audio” problem happens across mobile networks, VoIP apps, and even traditional landlines, and it often points to a specific break in the complex audio path.
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Understanding why this occurs requires looking beyond the surface. A phone call is not a single stream of sound but a pair of independent audio channels: one carrying your voice out, and another carrying the other person’s voice in. If one of these paths fails while the other remains intact, the result is a call where only one side can hear.
How phone audio actually travels
When you speak, your phone’s microphone converts sound waves into digital signals. These signals pass through software layers, network protocols, and carrier infrastructure before reaching the other person’s device, where they are converted back into sound. At the same time, the reverse process is happening for incoming audio. Because these paths are separate, it is entirely possible for one to function while the other breaks down.
This separation explains why one-way audio is far more common than a complete call drop. The connection still exists, but only half of the audio pipeline is working.
Microphone and hardware issues
One of the most common causes is a malfunctioning or obstructed microphone. Dust, debris, or a phone case can partially block the mic opening. Hardware damage from drops or water exposure can also affect only the microphone while leaving speakers untouched. In these cases, you can hear the other person perfectly, but your voice never makes it into the system.
Bluetooth accessories add another layer of complexity. If your phone is connected to a headset or car system with a faulty microphone, the phone may route your voice input there instead of using its built-in mic, resulting in silence on the other end.
Software, permissions, and app conflicts
On smartphones, apps must have explicit permission to access the microphone. If a calling app loses this permission due to an update, system bug, or user setting change, it may still receive audio but fail to send it. Background apps can also hijack the microphone, preventing the call app from using it correctly.
Operating system glitches, outdated apps, or corrupted cache data can interfere with audio encoding or routing. This is especially common in VoIP calls, where software handles much of what traditional carriers manage automatically.
Network and carrier-related causes
One-way audio can also stem from network problems. Firewalls, NAT configurations, or carrier routing errors may block outgoing audio packets while allowing incoming ones. In VoIP and Wi-Fi calling, improper network traversal settings can prevent your voice data from reaching the other party, even though their voice reaches you.
Carrier-side issues, such as codec mismatches or temporary server faults, can also affect only one direction of audio. These problems often appear suddenly and resolve just as mysteriously.
How to fix
1. Start with the obvious (but important) checks
First, make sure nothing is physically blocking the microphone. Phone cases, screen protectors, dirt, or pocket lint can partially or fully cover the mic hole. Try removing the case and gently cleaning the microphone area.
Also check whether the phone is muted on your device, not just in the app. Some calls fail simply because the mute button was tapped accidentally.
2. Test the microphone itself
Open a voice recorder or video recording app and record yourself speaking. Play it back.
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If you hear your voice clearly, the microphone hardware is likely fine.
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If the recording is silent or distorted, the issue is almost certainly hardware-related, and no app setting will fix it.
If you’re using Bluetooth (earbuds, headset, car system), disconnect it and try the call again using the phone directly. Faulty Bluetooth microphones are a very common cause of one-way audio.
3. Check app permissions and audio settings
For app-based calls (WhatsApp, Zoom, Teams, FaceTime, etc.), go into your phone’s settings and confirm the app has microphone permission enabled. Updates can silently reset permissions.
Inside the app itself, look for:
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Audio input selection (make sure the correct mic is chosen)
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Call audio settings or “reset audio” options
If the app allows it, switch audio sources during the call (speaker → earpiece → speaker) to force the system to re-route sound.
4. Restart and isolate the problem
A simple restart can fix temporary audio-routing bugs.
Then test:
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Call using a different app
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Call a different person
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Call over cellular data instead of Wi-Fi (or vice versa)
If the problem only happens in one app, reinstall it.
If it happens across all apps and regular phone calls, the issue is likely system-level or hardware-related.
5. Network-related fixes
For VoIP or Wi-Fi calling:
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Turn off VPNs or firewalls
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Switch networks (Wi-Fi ↔ mobile data)
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Disable Wi-Fi calling temporarily
One-way audio often happens when outgoing audio packets are blocked while incoming ones pass through.
6. Update software and reset settings
Make sure your phone’s operating system and calling apps are fully updated. Audio bugs are frequently fixed in updates.
If the problem persists, consider resetting network settings (this won’t delete data, but it will reset Wi-Fi, Bluetooth, and carrier configs).
7. When it’s likely hardware damage
If:
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Voice recordings fail
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The issue happens on every app and call
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Headsets don’t help
Then the microphone itself may be damaged (often from drops or water exposure). In that case, professional repair or using an external mic (wired or Bluetooth) is the most reliable solution.
Why it can be intermittent
A particularly confusing aspect of one-way audio is its inconsistency. A call may work perfectly one moment and fail the next. This is often due to fluctuating network conditions, automatic switching between Wi-Fi and cellular data, or dynamic audio routing when devices connect or disconnect from accessories.
Because multiple systems are involved, small changes can tip a marginal setup into failure.
In the end, one-way audio is less a single problem and more a symptom of where modern communication can fracture. It highlights how many independent components must cooperate for something as simple as a conversation to work seamlessly.
By recognizing that incoming and outgoing audio are separate paths—each with its own hardware, software, and network dependencies—you can better diagnose the issue. Whether the cause is a blocked microphone, a misbehaving app, or a network quirk, understanding the underlying mechanics turns a confusing silence into a solvable problem.