Hi All,

I have a serious problem with SIP call flow over SER.
My SER don't retransmit ACK first and after that don't retransmit BYE message, too.
Can any one advice me? what can be a reason? 
Here are call flow and ser.cfg.
 
 

SIPPHONE------------------------SER--------------------------CISCO SIP GW
|-------------INVITE------------>|                                |
|<----------TRying---------------|                                |
|                                |-----------INVITE-------------->|
|                                |<----------TRying---------------|
|                                |<------------183----------------|
|<------------183----------------|                                |                                 
|                                |<-------------OK----------------|
|---------------ther is two way RTP channel ----------------------|
|<-------------OK----------------|                                |
|--------------ACK-------------->|                                |                                  
|                                |<-------------OK----------------|
|<-------------OK----------------|                                |
|--------------ACK-------------->|                                |
|                                |<-------------OK----------------|
|<-------------OK----------------|                                |
|--------------ACK-------------->|                                |
|                                |<-------------OK----------------|
|<-------------OK----------------|                                |
|--------------ACK-------------->|   SER don't retransmit ACK     |
|                                | and Cisco timedout after 19sec |
|                                |<-------------BYE---------------|
|                                |<-------------BYE---------------|
|                                |<-------------BYE---------------|
|     SER don't retransmit BYE   |<-------------BYE---------------|
|                                |<-------------BYE---------------|
 
 
 
 
#
# $Id: ser.cfg,v 1.21.4.1 2003/11/10 15:35:15 andrei Exp $
# ----------- global configuration parameters ------------------------
 
debug=8
fork=yes
log_stderror=yes
 
check_via=no      # (cmd. line: -v)
dns=no           # (cmd. line: -r)
rev_dns=no      # (cmd. line: -R)
port=5060
#children=4
fifo="/tmp/ser_fifo"
 
# ------------------ module loading ----------------------------------
loadmodule "/usr/local/lib/ser/modules/sl.so"
loadmodule "/usr/local/lib/ser/modules/tm.so"
loadmodule "/usr/local/lib/ser/modules/rr.so"
loadmodule "/usr/local/lib/ser/modules/maxfwd.so"
loadmodule "/usr/local/lib/ser/modules/usrloc.so"
loadmodule "/usr/local/lib/ser/modules/registrar.so"
 
loadmodule "/usr/local/lib/ser/modules/auth.so"
loadmodule "/usr/local/lib/ser/modules/auth_radius.so"
 
# ----------------- setting module-specific parameters ---------------
modparam("usrloc", "db_mode",   0)
modparam("rr", "enable_full_lr", 1)
# -------------------------  request routing logic -------------------
 
route{
 
     if (!mf_process_maxfwd_header("10")) {
           sl_send_reply("483","Too Many Hops");
           break;
     };
     if ( msg:len > max_len ) {
           sl_send_reply("513", "Message too big");
           break;
     };
 
     # authenticate register message using radius
     if (method=="REGISTER") {
           # Uncomment this if you want to use digest authentication
           if (!radius_www_authorize("")) {
                 www_challenge("", "0");
                 break;
           };
           save("location");
           break;
     };
 
     # route (proxy) invite message to gateway
     if (method=="INVITE") || (method=="CANCEL") {
           # Uncomment this if you want to use digest authentication
           if (!radius_www_authorize("")) {
                 www_challenge("", "0");
                 break;
           };
 
           record_route();
           rewritehostport("cisco_sip_gw_ip:5060");
           if (!t_relay()) {
                 sl_reply_error();
           };
           break;
     };
}