I configured connecting 2 Asterisk Servers via SIP TRUNK without NAT. Now, I am trying to connect 2 Asterisk Servers via SIP TRUNK with NAT: My system likes as: SIP1----->Asterisk Server1----->NAT1------>INTERNET<-----NAT2<-----AsteriskServer2<---SIP2  But it hasn't worked yet. I have some problem with NAT.  So, I would like to post my configuration to be get your helps.  Assuming Asterisk Server1 has IP local address is: 192.168.70.129 and IP Public(IP of modem ADSL) is 118.68.162.111 Asterisk Server 2 has IP local address is: 192.168.174.128 and IP Public(IP of modem ADSL) is 118.68.156.3 At Server1, I did: sip.conf [server2] nat=yes canreinvite=yes externip = 118.68.156.3  localnet = 192.168.174.128/255 localnet = 192.168.174.128/255.255.255.0  externrefresh = 60 type=peer host=118.68.156.3 context=inbound [1400] type=friend host=dynamic  context=outbound extensions.conf [Inbound] exten => _14XX,1,Answer exten => _14XX,2,wait(1) exten => _14XX,3,Dial(SIP/${EXTEN}) exten => _14XX,4,hangup() [outbound] exten => _13XX,1,Dial(SIP/${EXTEN}@server2)­ exten => _14XX,1,Goto(inbound,${EXTEN},1) At Server 2: sip.conf [server1]  nat=yes canreinvite=yes externip = 118.68.162.111  localnet = 192.168.70.129/255 localnet = 192.168.70.129/255.255.255.0  externrefresh = 60 type=peer  host=118.68.162.111 context=inbound  [1300] type=friend host=dynamic context=outbound  extensions.conf  [Inbound]  exten => _13XX,1,Answer  exten => _13XX,2,wait(1) exten => _13XX,3,Dial(SIP/${EXTEN}) exten => _13XX,4,hangup() [outbound] exten => _14XX,1,Dial(SIP/${EXTEN}@server2)­ exten => _13XX,1,Goto(inbound,${EXTEN},1)  So, please take a look and give me some ways to fix them. Thanks a lot

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