hello dears 

when i'm using kamailio 5.2 as IMS i'm facing the following NAT issue :

• when p-cscf handle a call from user1 to user2 that pre-registered on private address "192.X.X.X" (on another LAN) the user can't receive the invite message .

in another word:
proxy ip : 10.192.X.X

the call scenario : user1 ---invite----> user2 (not arrived)

• when p-cscf handle a call from user2 that pre-registered on private IP "192.X.X.X" (on another LAN) to  user1 the user receive the invite message  .

the call scenario : user2 ---invite----> user1 (arrived)

• when both of the user on different LANs the message 200 OK doesn't arrive to proxy :\ 

so based on that does any one has an experiment with NAT handling & nathelper module and how to configure it on P-cscf .