Asterisk app_amd for FreeSWITCH

This is an implementation of Asterisk's answering machine detection (voice activity detection) for FreeSWITCH.

Currently, in limited testing, we are about to get satisfactory results in determining what is a human and what is a machine, but there is much more to do:

• Emit events when a decision is made (Not sure, Machine, or Human).
• Make sure that we are unlocking and cleaning up where necessary.

Building as a part of FreeSwitch source tree

To build module as a part of FreeSwitch source tree perform following steps:

• Add it as a git submodule git submodule add --name webitel-mod_amd https://github.com/webitel/mod_amd src/mod/applications/mod_amd
• Add src/mod/applications/mod_amd/Makefile to AC_CONFIG_FILES of configure.ac
• Add applications/mod_amd to modules.conf
• Build entire FreeSwitch project or module only

Sample Configuration

Just put a file like this in your freeswitch installation, in conf/autoload_configs/amd.conf.xml

<configuration name="amd.conf" description="mod_amd Configuration">
  <settings>
    <param name="silence_threshold" value="256"/>
    <param name="maximum_word_length" value="5000"/>
    <param name="maximum_number_of_words" value="3"/>
    <param name="between_words_silence" value="50"/>
    <param name="min_word_length" value="100"/>
    <param name="total_analysis_time" value="5000"/>
    <param name="after_greeting_silence" value="800"/>
    <param name="greeting" value="1500"/>
    <param name="initial_silence" value="2500"/>
  </settings>
</configuration>

Variables

After the AMD execution, the variable amd_result and amd_cause will be set.

The variable amd_result will return one of the following results:

• NOTSURE: take this value if total_analysis_time is over and decision could not be made
• HUMAN: if a human is detected
• MACHINE: if a human is detected

The variable amd_cause will return one of the following results:

• INITIALSILENCE (MACHINE)
• SILENCEAFTERGREETING (HUMAN)
• MAXWORDLENGTH (MACHINE)
• MAXWORDS (MACHINE)
• LONGGREETING (MACHINE)
• TOOLONG (NOTSURE)

Usage

Set a Dialplan as follow:

    <extension name="amd_ext" continue="false">
      <condition field="destination_number" expression="^5555$">
        <action application="answer"/>
          <action application="amd"/>
          <action application="playback" data="/usr/local/freeswitch/sounds/en/us/callie/voicemail/8000/vm-hello.wav"/>
          <action application="info"/>
          <action application="hangup"/>
      </condition>
    </extension>

The originate a call that will bridge to the amd_ext dialplan:

originate {origination_caller_id_number='808111222',ignore_early_media=true,originate_timeout=45}sofia/gateway/mygateway/0044888888888 5555