this is a bit sip centric but using the sip_req_host does make more sense in this case

git-svn-id: http://svn.freeswitch.org/svn/freeswitch/trunk@9916 d0543943-73ff-0310-b7d9-9358b9ac24b2

conf/dialplan/public.xml

@@ -38,7 +38,7 @@
       <condition field="${sip_req_params}" expression="domain_name=([A-Z-a-z0-9.]+)" break="never">
 	<!-- We need to export this so the B-Leg will have it after transfer too. -->
 	<action application="export" data="domain_name=$1"/>
-	<anti-action application="export" data="domain_name=$${domain}"/>
+	<anti-action application="export" data="domain_name=${sip_req_host}"/>
       </condition>
     </extension>