Skip to main content



Flite (aka Festival Lite) is a small embeddable TTS (Text to Speech) engine that's totally free.

Works on FreeBSD, Mac, Linux and Windows.

Don't load mod_cepstral and mod_flite at the same time. (symbol collision).

Voices are 16khz, and are:

  • slt (female voice)
  • rms (male voice)
  • awb (male voice)
  • kal (male voice)

Installing mod_flite

In modules.conf:

  • Uncomment asr_tts/mod_flite;

Edit the modules.conf at the top level of your src directory and NOT to be confused with the freeswitch/conf/modules.conf.xml file which you will also have to edit later - see below). This installation has been written assuming that you are going to be compiling this module.

Comment out asr_tts/mod_cepstral from the same file. Both modules cannot be used together.

  • Run make, make install.

In freeswitch/conf/autoload_configs/modules.conf.xml:

  • Uncomment <load module="mod_flite"/>
  • Comment out <load module="mod_cepstral"/>

Using mod_flite

    <extension name="flite">
<condition field="destination_number" expression="^9886$">
<action application="set" data="tts_engine=flite"/>
<action application="set" data="tts_voice=kal"/>
<action application="speak" data="This is flite on FreeSWITCH"/>

To set volume at your desired level:

 <action application="set_audio_level" data="write 4"/>
<action application="set_audio_level" data="read 4"/>

write for output audio stream and read for incoming audio stream. read and write can take integral values from 4 to -4