This is an implementation of Asterisk's answering machine detection (voice activity detection) for FreeSWITCH.
To build module as a part of FreeSwitch source tree perform following steps:
- Add it as a git submodule
git submodule add --name mod_amd https://github.com/silviucpp/mod_amd src/mod/applications/mod_amd - Add
src/mod/applications/mod_amd/MakefiletoAC_CONFIG_FILESofconfigure.ac - Add
applications/mod_amdtomodules.conf - Build entire FreeSwitch project or module only
Add into FreeSwitch installation, in conf/autoload_configs/mod_amd.conf.xml the following content or the template file you can find into conf folder.
initial_silence- is maximum initial silence duration before greeting. If this is exceeded, the result is detection as aMACHINE.greeting- is the maximum length of a greeting. If this is exceeded, the result is detection as aMACHINE.after_greeting_silence- is the silence after detecting a greeting. If this is exceeded, the result is detection as aHUMAN.total_analysis_time- is the maximum time allowed for the algorithm to decide on whether the audio represents aHUMAN, or aMACHINE.maximum_word_length- is the maximum duration of a word to accept. If exceeded, then the result is detection as aMACHINE.min_word_length- is the minimum duration of Voice considered to be a word.between_words_silence- is the minimum duration of silence after a word to consider the audio that follows to be a new word.maximum_number_of_words- is the maximum number of words in a greeting If this is exceeded, then the result is detection as aMACHINE.silence_threshold- the average level of noise from 0 to 32767 which if not exceeded, should be considered silence.silence_not_sure- enable or disable theNOT_SUREresult. In case is disabledMACHINEis sent instead.
<configuration name="mod_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"/>
<param name="silence_not_sure" value="no"/>
</settings>
</configuration>After the AMD execution the mod_amd::info event is triggered and the variable amd_result and amd_cause will be set.
The variable amd_result will contain one of the following values:
NOT_SURE- take this value iftotal_analysis_timeis over and decision could not be made andsilence_not_sureis on.HUMAN- if a human is detected.MACHINE- if a human is not detected.
The variable amd_cause will return one of the following values:
INITIAL_SILENCE(MACHINE)SILENCE_AFTER_GREETING(HUMAN)MAX_WORD_LENGTH(MACHINE)MAX_WORDS(MACHINE)LONG_GREETING(MACHINE)TOO_LONG(NOTSURE)
Set a Dialplan as follow (see conf/dialplan.xml):
<extension name="amd_ext" continue="false">
<condition field="destination_number" expression="^5555$">
<action application="answer"/>
<action application="mod_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