Here's the tail /var/log/messages and my ser.cfg. Can you see anythingwrong? My computer have only one NIC and is assigned static IP192.168.1.17. May 10 11:31:41 localhost ser: WARNING: fix_socket_list: could not rev. resolve 192.168.1.17 May 10 11:31:41 localhost ser: WARNING: fix_socket_list: could not rev. resolve 192.168.1.17 May 10 11:31:41 localhost /usr/local/sbin/ser[3085]: Maxfwd module- initializing May 10 11:32:19 localhost ser: WARNING: fix_socket_list: could not rev. resolve 192.168.1.17 May 10 11:32:19 localhost ser: WARNING: fix_socket_list: could not rev. resolve 192.168.1.17 May 10 11:32:19 localhost ser[3096]: Maxfwd module- initializing /usr/local/etc/ser/ser.cfg # # $Id: ser.cfg,v 1.25.2.1 2005/02/18 14:30:44 andrei Exp $ # # simple quick-start config script # # ----------- global configuration parameters ------------------------ #debug=3         # debug level (cmd line: -dddddddddd) #fork=yes #log_stderror=no    # (cmd line: -E) /* Uncomment these lines to enter debugging mode fork=no 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 ---------------------------------- # Uncomment this if you want to use SQL database #loadmodule "/usr/local/lib/ser/modules/mysql.so" 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/textops.so" # Uncomment this if you want digest authentication # mysql.so must be loaded ! #loadmodule "/usr/local/lib/ser/modules/auth.so" #loadmodule "/usr/local/lib/ser/modules/auth_db.so" # ----------------- setting module-specific parameters --------------- # -- usrloc params -- modparam("usrloc", "db_mode",   0) # Uncomment this if you want to use SQL database # for persistent storage and comment the previous line #modparam("usrloc", "db_mode", 2) # -- auth params -- # Uncomment if you are using auth module # #modparam("auth_db", "calculate_ha1", yes) # # If you set "calculate_ha1" parameter to yes (which true in this config), # uncomment also the following parameter) # #modparam("auth_db", "password_column", "password") # -- rr params -- # add value to ;lr param to make some broken UAs happy modparam("rr", "enable_full_lr", 1) # -------------------------  request routing logic ------------------- # main routing logic route{     # initial sanity checks -- messages with     # max_forwards==0, or excessively long requests     if (!mf_process_maxfwd_header("10")) {         sl_send_reply("483","Too Many Hops");         break;     };     if (msg:len >=  2048 ) {         sl_send_reply("513", "Message too big");         break;     };         # we record-route all messages -- to make sure that     # subsequent messages will go through our proxy; that's     # particularly good if upstream and downstream entities     # use different transport protocol     if (!method=="REGISTER") record_route();        # subsequent messages withing a dialog should take the     # path determined by record-routing     if (loose_route()) {         # mark routing logic in request         append_hf("P-hint: rr-enforced\r\n");         route(1);         break;     };     if (!uri==myself) {         # mark routing logic in request         append_hf("P-hint: outbound\r\n");         route(1);         break;     };     # if the request is for other domain use UsrLoc     # (in case, it does not work, use the following command     # with proper names and addresses in it)     if (uri==myself) {         if (method=="REGISTER") { # Uncomment this if you want to use digest authentication #            if (!www_authorize("iptel.org", "subscriber")) { #                www_challenge("iptel.org", "0"); #                break; #            };             save("location");             break;         };         lookup("aliases");         if (!uri==myself) {             append_hf("P-hint: outbound alias\r\n");             route(1);             break;         };         # native SIP destinations are handled using our USRLOC DB         if (!lookup("location")) {             sl_send_reply("404", "Not Found");             break;         };     };     append_hf("P-hint: usrloc applied\r\n");     route(1); } route[1] {     # send it out now; use stateful forwarding as it works reliably     # even for UDP2TCP     if (!t_relay()) {         sl_reply_error();     }; } On 5/9/06, sip <sip(a)arcdiv.com> wrote: This is usually an indication that there was an error inthe ser.cfg file.  If you look in the system messages log(/var/log/messages), it should give you more specific information aboutwhich error occurred. N. On Tue, 9 May 2006 14:00:49 +0700, Linh Pham wrote -- Best regards, Linh Pham Research & Development Center POSTEF 61 Tran Phu, Hanoi, Vietnam