One-way or no audio

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.

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.
• 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.

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 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).