[Serusers] bad call flow

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; }; }