freeswitch/conf/directory/default.xml

<include>
  <!--the domain or ip (the right hand side of the @ in the addr-->
  <domain name="$${domain}">
    <params>
      <param name="dial-string" value="{presence_id=${dialed_user}@${dialed_domain},transfer_fallback_extension=${dialed_user}}${sofia_contact(${dialed_user}@${dialed_domain})}"/>
    </params>

    <variables>
      <variable name="record_stereo" value="true"/>
    </variables>

    <X-PRE-PROCESS cmd="include" data="default/*.xml"/>
  </domain>
</include>