Required Kamailio,WebRTC,Freeswitch freelancer for setup ICE STUN for Freeswitch on Kazoo CentOS7 job

I have a VoIP server called Kazoo (Freeswitch, Kamailio, Erlang) that is configured to use websockets. Everything works fine except that when I'm using a browser phone, I have no audio inbound direction from cell phones. Outbound calls have no issue, i get sound both ways but when someone calls in from a cellphone I get no audio both ways.
My VoIP server (Kazoo) in hosted on Google Cloud behind NAT. I am advertising my public IP IN kAMAILIO so I can register end points.
What I need is an ICE/STUN server setup to enable me to have audio both ways whenever I get an inbound call from a cellphone.
I want to work with someone who is very familiar with KAZOO and FreeSWITCH. I will like to have documentation of the implementation so I can do it myself next time.

Skills & Expertise Required

Kamailio WebRTC Freeswitch