Thank you *Varghese Paul* for looking my post. My topology is like this: SIP trunk provider ---------- my FreeSwitch -------------- Elastix ------------ X-Lite Today, I make it work on the public IP asterisk registered to public IP FreeSwitch. original issue might be I put the wrong register string in Elastix. ( should be username:passwd@realm and yesterday was username:passwd@realm/username ) Means I can accept the phone from SIP trunk provider to FreeSwitch, and forward to Elastix, however, in Elastix, can not get my real DID ( in my Asterisk log, showes Executing [s@from-pstn:1] Set("SIP/ABCDE-0000007f", "__FROM_DID=s") in new stack So I guess, I need put application "set“ in my dialplan of my freeswitch, right ? my current public dialplan of my number from SIP trunk provider like this. <extension name="abctel-inbound-1234"> <condition field="destination_number" expression="^(6472221234)$"> <action application="set" data="domain_name=$${domain}"/> <action application="bridge" data="user/$1"/> </condition> </extension> and in my directory/default, I have a file 6472221234.xml <include> <user id="6472221234"> <params> <param name="password" value="$${default_password}"/> <param name="vm-password" value="1234"/> </params> <variables> <variable name="toll_allow" value="domestic,international,local"/> <variable name="accountcode" value="6472221234"/> <variable name="user_context" value="default"/> <variable name="effective_caller_id_name" value="ABCDE"/> <variable name="effective_caller_id_number" value="6472221234"/> <variable name="outbound_caller_id_name" value="ABCDE"/> <variable name="outbound_caller_id_number" value="$${outbound_caller_id}"/> <variable name="callgroup" value="techsupport"/> </variables> </user> </include> What I expect is in Asterisk side, should be my DID from FreeSwitch to Asterisk as "__FROM_DID=6472221234" What's my missing in Dialplan ? or director /default / 6472221234.xml ? in the freeswitch wiki, it said exten to exten need put context = from-internal, and I did this by from-pstn. my Asterisk trunk like this: host=1.1.1.1 username=6472221234 secret=xxxxxxxxxxxxxxx type=friend port=5060 qualify=no insecure=very dtmfmode=rfc2833 deny=0.0.0.0/0.0.0.0 permit=1.1.1.1/255.255.255.255 jbenable=no disallow=all context=from-pstn allow=ulaw trustpid=yes sendrpid=yes register string is : 6472221234:xxxxxxxxxxxx@1.1.1.1 any idea please let me know. -------------------------------------------- My another problem here is the NAT I guess, if my asterisk in my LAN (FreeSwitch still on the public IP. ) the same register shows in my asterisk cli abc*CLI> sip show registry Host dnsmgr Username Refresh State Reg.Time 1.1.1.1:5060 N 1009 120 Request Sent can not register on the FreeSwitch. Thank you again. Sincerely, Shaw