freeswitch/conf/sbc/dialplan/features.xml

<!-- http://wiki.freeswitch.org/wiki/Dialplan_XML -->
<include>
  <context name="features">

    <!-- In call Transfer for phones without a transfer button -->
    <extension name="dx">
      <condition field="destination_number" expression="^dx$">
	<action application="answer"/>
	<action application="read" data="11 11 'tone_stream://%(10000,0,350,440)' digits 5000 #"/>
	<action application="execute_extension" data="is_transfer XML features"/>
      </condition>
    </extension>

    <extension name="is_transfer">
      <condition field="destination_number" expression="^is_transfer$"/>
      <condition field="${digits}" expression="^(\d+)$">
	<action application="transfer" data="-bleg ${digits} XML default"/>
	<anti-action application="eval" data="cancel transfer"/>
      </condition>
    </extension>

    <!-- Used to transfer both legs into a conference -->
    <extension name="cf">
      <condition field="destination_number" expression="^cf$">
	<action application="answer"/>
	<action application="transfer" data="-both 30${dialed_extension:2} XML default"/>
      </condition>
    </extension>

    <extension name="please_hold">
      <condition field="destination_number" expression="^(10[01][0-9])$">
	<action application="set" data="transfer_ringback=$${hold_music}"/>
	<action application="answer"/>
	<action application="sleep" data="1500"/>
	<action application="playback" data="ivr/ivr-hold_connect_call.wav"/>
	<action application="transfer" data="$1 XML default"/>
      </condition>
    </extension>

    <extension name="is_secure">
      <!-- Only Truly consider it secure if its TLS and SRTP --> 
      <condition field="${sip_via_protocol}" expression="tls"/>
      <condition field="${rtp_secure_media_confirmed}" expression="^true$">
	<action application="sleep" data="1000"/>
	<action application="playback" data="misc/call_secured.wav"/>
	<anti-action application="eval" data="not_secure"/>
      </condition>
    </extension>

  </context>
</include>