I made two listeners:
listen=udp:10.130.0.23:5070 #to pbx in lan (I don`t want to put via header with 178.0.0.169)
listen=udp:10.130.0.23:5060 advertise 178.0.0.169:5060 #to internet (UserAgent need to get via header with 178.0.0.169  )

mhomed = 1 # I think It not useful  for my case

UserAgent send Register and Invite to 178.0.0.169:5060, Kamailio get it on udp:10.130.0.23:5060

Kamailio Relay it to   udp:10.130.0.23:5070

My pbx get requests from  udp:10.130.0.23:5070 with via header 10.130.0.23

Responses to UserAgent go from  udp:10.130.0.23:5060 with via 178.0.0.169

In  RELAY block:
if ($Ru == «udp:10.130.0.23:5070») {
#set_send_socket(«udp:10.130.0.23:5060»);
$fs = «udp:10.130.0.23:5060»;
#force_send_socket(«udp:10.130.0.23:5060»);
} else {
#set_send_socket(«udp:10.130.0.23:5070»);
$fs = «udp:10.130.0.23:5070»;
}
#$fs = «udp:10.130.0.23:5070»;
if (!t_relay()) {
sl_reply_error();
}

route[REGISTRAR] {

        if ($rd == "mydomain.ru" || $rd == "mydomain2.ru") {

          set_send_socket("udp:10.130.0.23:5070");

         }

}

It works for requests from UserAgent to PBX. But INVITE from my pbx to UserAgent goes only through udp:10.130.0.23:5070 ,  Kamailio realy it to internet from udp:10.130.0.23:5070

I get error in syslog:  (pv [pv_branch.c:62]: pv_get_branchx_helper(): error accessing branch [0])

I tried set_send_socket(«udp:10.130.0.23:5070»); and $fs = «udp:10.130.0.23:5070»;

Why I can`t relay outgoing requests to internet through another socket? 

Best regards,
Alex