[Serusers] diagram for NAT users

Dear Users I was wondering how is the diagram for NAT users, maybe this NO NAT ENV UA----INVITE-------> SER----------INVITE---------->TERMINATION UA<----ACK-------> SER<----------ACK----------TERMINATION UA<----------------------RTP TRAFF------------------> TERMINATION NAT ENV WITH , NATHELPER NAT-UA----INVITE-------> SER----------INVITE---------->TERMINATION NAT-UA<----ACK-------> SER<----------ACK----------TERMINATION NAT-UA<-----RTP TRAFF<------>SER WITH NATHELPER<---------RTP TRAFF----------------> TERMINATION so the trafic in a nat environment is nat-ua to ser , ser to termination, and viceversa termination to ser, ser to nat-ua any help will be thanks. gustavo villegas