[Serusers] Please help...

I have three UA UA1 -> beeplove(a)iptel.org (Windows Messenger) UA2 -> beeplove(a)projuktee.com (Kphone) UA3 -> someone(a)projuktee.com (Windows Messenger) These three UAs, registering from outside of my network but behind NAT. I can communicate between, UA1 <=> UA2 and UA1 <=> UA3 but not between UA2 <=> UA3 I am running ser-0.9.0 with rtpproxy on the same machine. my ser is behind NAT too. Would anybody please help me? Thanks, MOhammad here is my ser.cfg # ----------- global configuration parameters ------------------------ debug=4 # debug level (cmd line: -dddddddddd) fork=no log_stderror=yes check_via=no # (cmd. line: -v) dns=no # (cmd. line: -r) rev_dns=no # (cmd. line: -R) listen=192.168.71.2 alias=projuktee.com port=5060 children=10 fifo="/tmp/ser_fifo" fifo_db_url="mysql://ser:heslo@localhost/ser" # ------------------ module loading ---------------------------------- 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/nathelper.so" loadmodule "/usr/lib/ser/modules/acc.so" loadmodule "/usr/lib/ser/modules/auth.so" loadmodule "/usr/lib/ser/modules/auth_db.so" # ----------------- setting module-specific parameters --------------- # -- auth params -- modparam("auth_db", "db_url", "mysql://ser:heslo@localhost/ser") # -- auth_db params -- modparam("auth_db", "db_url", "mysql://ser:heslo@localhost/ser") modparam("auth_db", "calculate_ha1", 0) modparam("auth_db", "password_column", "ha1") modparam("auth_db", "password_column_2", "ha1b") # -- usrloc params -- modparam("usrloc", "db_url", "mysql://ser:heslo@localhost/ser") modparam("usrloc", "db_mode", 1) modparam("usrloc", "timer_interval", 5) # -- register params -- modparam("registrar", "nat_flag", 6) # -- nathelper params -- modparam("nathelper", "natping_interval", 10) modparam("nathelper", "ping_nated_only", 1) # -- rr params -- modparam("rr", "enable_full_lr", 1) # -- acc params -- modparam("acc", "log_flag", 1) modparam("acc", "log_missed_flag", 2) modparam("acc", "log_level", 2) modparam("acc", "log_fmt", "cdfimorstup") modparam("acc", "early_media", 1) modparam("acc", "failed_transactions", 1) modparam("acc", "report_ack", 1) # ------------------------- request routing logic ------------------- # main 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; }; if (!method=="REGISTER") record_route(); if (loose_route()) { append_hf("P-hint: rr-enforced\r\n"); route(1); break; }; if (!uri=~"projuktee.com") { append_hf("P-hint: outbound\r\n"); route(1); break; }; if (uri=~"projuktee.com") { if (method=="REGISTER") { if (!www_authorize("projuktee.com", "subscriber")) { www_challenge("projuktee.com", "0"); setflag(1); break; }; save("location"); break; }; lookup("aliases"); if (!uri=~"projuktee.com") { append_hf("P-hint: outbound alias\r\n"); route(1); break; }; if (!lookup("location")) { sl_send_reply("404", "Not Found"); break; }; }; append_hf("P-hint: usrloc applied\r\n"); route(1); } route[1] { if (!t_relay()) { sl_reply_error(); }; }