# One-way or no audio

> Fix calls where you can't hear the other person, they can't hear you, or neither of you hears anything.

- URL: https://kb.voipcloud.online/au/troubleshooting/one-way-or-no-audio/
- Section: Troubleshooting
- Type: troubleshooting
- Applies to: All countries
- Last reviewed: 2026-11-09

## Symptom

The call connects, but:

- you can't hear the other person, or they can't hear you (one-way audio); or
- neither of you hears anything (no audio).

Note which side can't hear. It helps find the cause.

## Quick checks

1. **Check the mute button**, the volume, and the headset or handset cable. Try the call on speakerphone or the handset instead of a headset.
2. **Webphone:** check the browser or app is allowed to use your microphone, and the right microphone and speaker are selected.
3. **Is it every call, or only some?** If it only happens with one caller or one destination, the problem may be on their side.
4. **Is it every phone at the site?** If yes, the router or firewall is the most likely cause.

## Likely causes and fixes

### 1. The microphone or headset

**Fix:**

- Try a different headset, or the phone's handset.
- On a computer, check the operating system's sound settings use the right devices, and that the headset's drivers are installed.
- In the Webphone, allow microphone access in the browser. See [Webphone troubleshooting](https://kb.voipcloud.online/au/phones-and-apps/webphone/webphone-troubleshooting/).

### 2. The router or firewall blocks the audio

Call audio travels separately from the call signalling. A firewall can let the call connect but block the audio in one or both directions. Routers that translate addresses (NAT) can also send the audio to the wrong place.

**Fix:**

- Allow the phone system's audio traffic in both directions in your firewall. Ask the support team for the addresses and ports to allow; see [Network requirements](https://kb.voipcloud.online/au/getting-started/network-requirements/).
- Turn off **SIP ALG** on the router. It rewrites call signalling and often breaks audio.
- Restart the router, especially after recent changes.

### 3. NAT on a Yealink phone

Setting a STUN server lets the phone find its public address, which can fix one-way audio behind NAT. Ask the support team for the STUN server address to use.

**Note:** Menus can change between versions. If a label is different, check the vendor's own help.

1. In the phone's web interface, go to **Network** › **NAT**.
2. Under **STUN**, turn on **Active**, and enter the **STUN Server** and **STUN Port** (usually 3478).
3. Go to **Account** › **Register** and set **NAT** to **STUN**.
4. Click **Confirm**.

### 4. No matching audio codec

If the two sides can't agree on an audio codec, the call may fail or have no audio. A softphone may show **488 Not Acceptable Here**.

**Fix:** in the phone or softphone, allow the codecs listed under **Supported audio codecs** in the device's SIP credentials (**PBX** › **Devices**). See [Softphone errors](https://kb.voipcloud.online/au/phones-and-apps/softphones/softphone-errors/).

### 5. Test another network

To find out whether your network is the cause, connect the phone or computer to a different internet connection, such as a mobile hotspot, and make a test call. If the problem goes away, talk to your internet or IT provider about the router and firewall.

## When to contact support

[Create a support ticket](https://kb.voipcloud.online/au/support/support-tickets/) with:

- the date and time of an affected call (with your time zone);
- the number you called or that called you, and the user or device involved;
- which side couldn't hear: you, the other person, or both;
- the device type (Webphone, desk phone model, softphone);
- whether it happens on every call and every phone at the site, and what you've already tried (router changes, another network).