Call Progress Analysis

Requirement

Call progress analysis is needed in outbound campaign calls to determine whether the answering party is a human or a machine i.e. voicemail, answering machine etc.

Freeswitch Mods

CPA can be achieved via certain mods on Freeswitch.

Mod_rayo

Resources:

• https://developer.signalwire.com/freeswitch/FreeSWITCH-Explained/Modules/mod_rayo_3375450/

• https://files.speakerdeck.com/presentations/73b252a0f7ba01301fbe5276e331102d/Rayo_-_ClueCon_Weekly_2013-09-04.pdf

Usage:

• Native to Freeswitch, uses "Rayo" protocol.

• Deemed unnecessary for use.

• Complicated to set up with little to no guide on usage.

Mod_amd

Resources:

• https://github.com/seanbright/mod_amd

• https://sillycodes.com/asterisk-answering-machine-detection-amd-configuration/

Usage:

• Separate from Freeswitch.

• Detects whether human or machine has answered the call.

• Detection works by checking  if there is a greeting or initial silence and how long it silence lasts, the silence between words, among other parameters, over a period of time.

• Can be set up fairly easily via the following steps:

  1. Clone repo https://github.com/seanbright/mod_amd and move mod_amd folder under /usr/src/

  2. Run command 'export PKG_CONFIG_PATH=/usr/lib/pkgconfig/'

  3. Edit /usr/src/mod_amd/Makefile and comment out 'MODCFLAGS = -Wall -Werror'

  4. Run command 'make'.

  5. Moved the generated file mod_amd.so to /usr/lib/freeswitch/mod/.

  6. Create amd.conf.xml in /etc/freeswitch/autoload_configs/ and copy the given text in the section: https://github.com/seanbright/mod_amd#sample-configuration.

  7. Open fs_cli and run command 'load mod_amd'.

• Configure parameters in amd.conf.xml to tune according to expected machine/human behaviour.

• Run amd application during calls via:

  • For XML dialplan: <action application="amd" data=""/>

  • For Lua script: session:execute("amd")

• The amd will check for the configured duration whether the answered party is a machine or human.

• After the check is done, a channel variable amd_result is set to either HUMAN or MACHINE.

• Another channel variable amd_cause is also set, to describe why the answered party was flagged as a machine.

• May be CPU intensive.

• Requires much testing to configure the parameters for required cases.

Possible Integration:

• The dialer originates a call to the customer and runs a script provided with the agent extension as argument.

• The mod_amd detection is started once the call hits the gateway.

• If the customer does not answer, an automated message will play, which can either be TTS or a recording.

• Based on the parameters set in amd.conf.xml, the detection will give results similar to the following:

  • 

  • 

  • In either case, the call will be hung up.

• If the customer answers the call, then their voice will be detected and according to properly configured parameters, detected as human.

  • 

  • The call will bridged to an agent.

• In either scenarios, the amd_result variable will be set to match the detected entity (HUMAN or MACHINE)  and the amd_cause will contain the detection reason:

  • 

• Based on these set channel variables, if a machine answered the call:

  • The CIM will be notified via the END_CHAT intent to free up the agent.

  • Call result will be saved as MACHINE_DETECTED.

Mod_avmd

Resources:

• https://developer.signalwire.com/freeswitch/FreeSWITCH-Explained/Modules/mod_avmd_1049372/

Usage:

• Native to Freeswitch.

• Works by detecting beep at the end of voicemail/answering machine.

• Used by calling avmd_start during a call:

  • XML dialplan: <action application="avmd_start" data="inbound_channel=1,outbound_channel=1"/>

  • Lua script: session:execute("avmd_start","inbound_channel=1,outbound_channel=1")

• If a beep is detected:

  • A CUSTOM beep event is fired.

  • A channel variable avmd_detect is created and set to true.

Possible integration:

• The dialer originates a call as usual but with an additional parameter: execute_on_answer avmd_script.lua

  • This script contains the line session:execute("avmd_start","inbound_channel=1,outbound_channel=1") which starts mod_avmd detection

• If a voicemail/answering-machine beep is detect the following event is broadcast :

  • 

• This event can be detected in the dialer.

• The dialer will read the call UUID from the channel variables from this event.

• The dialer will hangup the call and stop avmd detection with avmd call_uuid stop.

• The post-call script will run and and detect that the avmd_detect variable was true.

  • The CIM will be notified via the END_CHAT intent to free up the agent.

  • Call result will be saved as MACHINE_DETECTED.