Although my question it's not related to Kamailio directly, but i think someone could help in this strange behavior

in our tests, we have some clients under private networks, where the provider of those networks implements CGNAT (NAT444) for it's customers to reach internet 

(Client Private IP) --->(Home router: Private to Private NAT)--->(FW with CGNAT)---------------------------->(Kamailio Proxy Public IP)

Registration is performing fine, but making calls from this client had strange problem as follow:

Client -------------INVITE--------------> Proxy

Proxy -------------Trying---------------->Client

Proxy--------------INVITE---------> Called Party

The called party should send Ringing msg, but the massage get lost somewhere and didn't reach to the Proxy. Although all the IP's in sip massages are public

i tried with STUN/TURN and NAThelper module solutions, but didn't help

is there any way to slove CGNAT with SIP in Kamailio? 

Thanks in Advance