Kakao Talk firewall ports for call audio

I am using Kakao Talk messaging and call functions on my iPhone 6. When I am using the mobile data network all functions fine. But when I connect to my home network, only the messaging works. When I attempt a call, it connects, but the audio is blocked -- neither I nor the person called can hear audio. Seems like I must have my firewall blocking ports needed by Kakao phone call audio.

Does anyone know the ports that I need to open?