How can I integrate FreePBX with Tailscale in my Home Assistant setup?

Hi everyone,
I recently installed the Tailscale add-on for Home Assistant and enabled subnet routes for remote access to my local network. I also have a FreePBX server for my home VoIP phone.

While calls work fine locally, I have issues when using the Linphone softphone outside my network. The local VoIP phone rings and I can hear the caller, but when I speak, the caller cannot hear me. When I connect my softphone to the local Wi-Fi, audio works perfectly.

Iam not sure if the problem lies with Tailscale, FreePBX, or my router’s IP address configuration. My goal is to make remote calls from my Android softphone over a 4G cellular signal to my home FreePBX VoIP phones. Has anyone encountered a similar issue?