No audio on a Poly phone

You can't hear the caller, or they can't hear you.

Rule out the device, then the network.

Steps

1. Try the handset, speaker and headset.If only one fails, it's that device.
2. Check Mute isn't on.
3. If outside calls have one-way audio, turn off SIP ALG on your router.
4. Ask your provider to check if internal calls work but outside calls don't.