Now UA3 <-> UA1 , UA1 <-> UA2 can make call successfuly via rtpproxy in bridge mode
but now when UA1 <-> UA2 , i want the call can be made not via rtpproxy ,
I think it should do some modification in ser.cfg to make this,
I have try some modification, but it doesn't works

check_via=no # (cmd. line: -v)
dns=no # (cmd. line: -r)
rev_dns=no # (cmd. line: -R)
port=5060
children=1
fifo="/tmp/ser_fifo"

loadmodule "/lib/ser/modules/sl.so"
loadmodule "/lib/ser/modules/tm.so"
loadmodule "/lib/ser/modules/rr.so"
loadmodule "/lib/ser/modules/maxfwd.so"
loadmodule "/lib/ser/modules/usrloc.so"
loadmodule "/lib/ser/modules/registrar.so"
loadmodule "/lib/ser/modules/textops.so"

# Uncomment this if you want digest authentication
# mysql.so must be loaded !
#loadmodule "/lib/ser/modules/auth.so"
#loadmodule "/lib/ser/modules/auth_db.so"

# 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")

# !! Nathelper
modparam("registrar", "nat_flag", 6)
modparam("nathelper", "natping_interval", 5) # Ping interval 30 s
modparam("nathelper", "ping_nated_only", 1) # Ping only clients behind NAT

# 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 >= max_len ) {
sl_send_reply("513", "Message too big");
break;
};

# !! Nathelper
# Special handling for NATed clients; first, NAT test is
# executed: it looks for via!=received and RFC1918 addresses
# in Contact (may fail if line-folding is used); also,
# the received test should, if completed, should check all
# vias for rpesence of received
if (nat_uac_test("3")) {
# Allow RR-ed requests, as these may indicate that
# a NAT-enabled proxy takes care of it; unless it is
# a REGISTER

if (method == "REGISTER" || ! search("^Record-Route:")) {
      log("LOG: Someone trying to register from private IP, rewriting\n");
      # This will work only for user agents that support symmetric
      # communication. We tested quite many of them and majority is
      # smart enough to be symmetric. In some phones it takes a configuration
      # option. With Cisco 7960, it is called NAT_Enable=Yes, with kphone it is
      # called "symmetric media" and "symmetric signalling".

      fix_nated_contact(); # Rewrite contact with source IP of signalling
      if (method == "INVITE")
      {
# jimmy added for test ++++++++++++++++++++++++++++++++
   if(src_ip=~"192.168.5.*")
   {
    ;
   }else{
# -----------------------------------------------------
          fix_nated_sdp("1"); # Add direction=active to SDP
    }

      };
      force_rport(); # Add rport parameter to topmost Via
      setflag(6);    # Mark as NATed
};
};

# 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 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) {

# Uncomment this if you want to use digest authentication
#   if (!www_authorize("iptel.org", "subscriber")) {
#    www_challenge("iptel.org", "0");
#    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);
}

# if client or server know to be behind a NAT, enable relay
if (isflagset(6)) {
# jimmy added for test ++++++++++++++++++++++++++++++++++++++++++++++
if(search("^(Contact|m): .*@(192\.168\.)"))
#if(src_ip=~"192.168.5.*")
{
;
}else{
# -------------------------------------------------------------------
force_rtp_proxy();
}

};

# NAT processing of replies; apply to all transactions (for example,
# re-INVITEs from public to private UA are hard to identify as
# NATed at the moment of request processing); look at replies
t_on_reply("1");

# send it out now; use stateful forwarding as it works reliably
# even for UDP2TCP
if (!t_relay()) {
sl_reply_error();
};
}

# !! Nathelper
onreply_route[1] {
    # NATed transaction ?
    if (isflagset(6) && status =~ "(183)|2[0-9][0-9]") {
# jimmy added for test ++++++++++++++++++++++++++++++++++++++++++++++
if(src_ip=~"192.168.5.*")
{
;
}else
{
        fix_nated_contact();
}
force_rtp_proxy();
# -------------------------------------------------------------------
    # otherwise, is it a transaction behind a NAT and we did not
    # know at time of request processing ? (RFC1918 contacts)
    } else if (nat_uac_test("1")) {
        fix_nated_contact();
    };
}