FS-9300: Add support for disabling sofia's 100 Trying via configuration, and sending 100 Trying from dialplan

conf/vanilla/dialplan/default.xml

@@ -828,5 +828,13 @@
       </condition>
     </extension>
 
+    <extension name="acknowledge_call">
+      <condition field="destination_number" expression="^(.*)$">
+	<action application="acknowledge_call"/>
+	<action application="ring_ready"/>
+	<action application="playback" data="$${hold_music}"/>
+      </condition>
+    </extension>
+
   </context>
 </include>

conf/vanilla/sip_profiles/internal.xml

@@ -418,5 +418,9 @@
     -->
     <!--<param name="renegotiate-codec-on-hold" value="true"/>-->
 
+    <!-- By default mod_sofia will send "100 Trying" in response to a SIP INVITE. Set this to false if
+         you want to turn off this behavior and manually send the "100 Trying" via the acknowledge_call application.
+    -->
+    <!--<param name="auto-invite-100" value="false"/>-->
   </settings>
 </profile>