Updated
Quick fix
First check mute, the headset and the volume. If calls still have one-way audio, restart the phone and the router. Persistent one-way audio is usually a router or firewall setting, such as SIP ALG, that needs your IT team or provider.
Step by step
Check the simple things
Make sure the phone isn’t muted, the headset is plugged in fully (or try the handset), and the volume is up.
Test the pattern
Does it happen on every call, only on outside calls, or only with one person? Write it down; it helps support find the cause quickly.
Try another phone or the app
If calls work in the desktop or mobile app but not on the desk phone, the phone or its cable may be the issue. If both have the problem, look at the network.
Restart the phone and router
Restart the phone, then restart the modem and router.
Check router and firewall settings
One-way audio is often caused by a router or firewall blocking the audio stream. SIP ALG and strict firewall rules are common culprits. Your IT team or phone provider can check these settings.
Contact support
Share the time of an affected call and the number called so the call can be traced.