Hi,
One‑way audio in Phone Link when calling landlines is typically a routing/compatibility issue between your PC’s audio stack, Bluetooth profiles HFP vs A2DP, and the carrier’s legacy voice path. Mobile calls often work because they use modern VoLTE routing, while landline calls expose the weaker path. Updating audio drivers, switching to a wired mic/headset, ensuring your headset is using the Hands‑Free HFP profile, and fully reinstalling Phone Link/companion app can mitigate it but in many cases this needs a Microsoft-side fix in Phone Link’s call bridge.
I hope this helps!