Use SER 0.8.12 stable release, enabled nathelper+rtpproxy for NAT traversal, forward 1(xxx)xxx-xxxx to SIp termiantion gateway, when the call was connected, PSTN gateway send 200 OK back, sip client ( behind NAT ) response with ACK ( which has branch value in Via head ), but when SER forward the ACK back to PSTN gateway, in Via header it includes branch=0, PSTN gateway refuse this ACk because it think the branch id is invalid, so call was dropped after 30- 60 seconds, what's wrong with that? I really appreciate if you met such problems before, thanks, and have a nice day.

Here is captured message between pstn gateway and ser:

SIP MESSAGE 4 65.22.14.3:42326(1) -> 182.156.33.10:5060(2) UDP Frame 13 10/Jul/04 13:29:33.6715 TimeFromPreviousSipFrame=3.4065 TimeFromStart=6.3374 SIP/2.0 200 OK Call-ID: 3164823746@192.168.0.102 From: sip:2103334444@182.156.33.10;user=phone;tag=1842950071 To: sip:021445333321@182.156.33.10;user=phone;tag=17810 Content-Length: 215 Content-Type: application/sdp CSeq: 1 INVITE Via: SIP/2.0/UDP 182.156.33.10;branch=z9hG4bK2681.4c495f05.0,SIP/2.0/UDP 192.168.0.102:5060;rport=64069;received=65.33.22.6 Contact: sip:19727925475@65.22.14.3:5060 Record-Route: sip:021445333321@182.156.33.10;ftag=1842950071;lr=on

SIP MESSAGE 5 182.156.33.10:5060(2) -> 65.22.14.3:42326(1) UDP Frame 23 10/Jul/04 13:29:33.7641 TimeFromPreviousSipFrame=0.0926 TimeFromStart=6.4300 ACK sip:19727925475@65.22.14.3:42326 SIP/2.0 Max-Forwards: 10 Record-Route: sip:021445333321@182.156.33.10;ftag=1842950071;lr=on Via: SIP/2.0/UDP 182.156.33.10;branch=0 Via: SIP/2.0/UDP 192.168.0.102:5060;rport=64069;received=65.33.22.6 From: sip:2103334444@182.156.33.10;user=phone;tag=1842950071 To: sip:021445333321@182.156.33.10;user=phone;tag=17810 Call-ID: 3164823746@192.168.0.102 CSeq: 1 ACK User-Agent: Cisco ATA v2.15 ata18x (020927a) Content-Length: 0

Here is the configuration file:

debug=0 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=8 listen=182.156.33.10 fifo="/tmp/ser_fifo" loadmodule "/usr/lib/ser/modules/nathelper.so" loadmodule "/usr/lib/ser/modules/mysql.so" loadmodule "/usr/lib/ser/modules/sl.so" loadmodule "/usr/lib/ser/modules/tm.so" loadmodule "/usr/lib/ser/modules/rr.so" loadmodule "/usr/lib/ser/modules/maxfwd.so" loadmodule "/usr/lib/ser/modules/usrloc.so" loadmodule "/usr/lib/ser/modules/registrar.so" loadmodule "/usr/lib/ser/modules/textops.so" loadmodule "/usr/lib/ser/modules/uri.so" loadmodule "/usr/lib/ser/modules/auth.so" loadmodule "/usr/lib/ser/modules/auth_radius.so" loadmodule "/usr/lib/ser/modules/acc.so"

modparam("usrloc", "db_mode", 2) modparam("usrloc", "db_mode", 2) modparam("rr", "enable_full_lr", 1) modparam("auth_radius", "radius_config", "/etc/radiusclient/radiusclient.conf") modparam("auth_radius", "service_type", 15) modparam("acc", "service_type", 15) modparam("acc", "radius_config", "/etc/radiusclient/radiusclient.conf") modparam("acc", "log_level", 2) modparam("acc", "radius_flag", 1) modparam("acc", "radius_missed_flag", 9) modparam("nathelper", "natping_interval", 10) 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; };

setflag(1); /* Radius Accouting */

loose_route(); record_route();

if (search("@192.168.*") || search("@10.*") || search("@172.16.*")) { setflag(2); force_rport(); fix_nated_contact(); };

/* For Radius Accounting */ if (method=="INVITE") { log(1, "INVITE: Radius Accounting\n"); setflag(1); /* Radius Accouting */

if (isflagset(2)) { force_rtp_proxy(); };

t_on_reply("1"); };

if (method=="MESSAGE") { log(1, "MESSAGE: Radius Accounting\n"); setflag(1); /* Radius Accouting */ };

if (method=="BYE" || method=="CANCEL") { log (1, "BYE or CANCEL: Radius Accounting\n"); setflag(1); /* Radius Accouting */ };

if (uri==myself) { if (method=="REGISTER") { if (!radius_www_authorize("")) { log(1, "REGISTER: Radius Challenging User\n"); www_challenge("", "0"); break; }; save("location"); break; };

lookup("aliases");

if (uri=~"sip:1[0-9][0-9][0-9]*@.*") { t_relay_to_udp("65.22.14.3", "5060"); break; }; # native SIP destinations are handled using our USRLOC DB if (!lookup("location")) { sl_send_reply("404", "Not Found"); break; }; }; setflag(1); if (!t_relay()) { sl_reply_error(); }; }

onreply_route[1] { if ( ((status=~"2[0-9][0-9]")||(status=~"183")) && (search("192.168.*") || search("@10.*") || search("172.16.*") )) { fix_nated_contact(); force_rtp_proxy(); }; }