DP+MySQL: AMD-Answering Machine Detection

Dialplan 範例

[amd-test]
exten => 9970,1,Noop(-- AMD Testing Start --)
 same => n,Background(beep)
 same => n,AMD()
 same => n,Noop(Detected: AMDSTATUS is ${AMDSTATUS})
 same => n,Goto(Status-${AMDSTATUS})
 same => n(Status-HUMAN),Noop(When AMDSTATUS  is <HUMAN>)
 same => n,WaitForSilence(2500)
 same => n,Playback(message-when-machine)
 same => n,Hangup
 same => n(Status-MACHINE),Noop(When AMDSTATUS  is <MACHINE>)
 same => n,Hangup
 same => n(Status-NOTSURE),Noop(When AMDSTATUS  is <NOTSURE>)
 same => n,Hangup
 same => n(Status-HANGUP),Noop(When AMDSTATUS is <HANGUP>)
 same => n,Hangup

amd.conf

;
; Answering Machine Detection Configuration
;

[general]
initial_silence = 2500          ; Maximum silence duration before the greeting.
                                ; If exceeded then MACHINE.
greeting = 1500                 ; Maximum length of a greeting. If exceeded then MACHINE.
after_greeting_silence = 800    ; Silence after detecting a greeting.
                                ; If exceeded then HUMAN
total_analysis_time = 5000      ; Maximum time allowed for the algorithm to decide
                                ; on a HUMAN or MACHINE
min_word_length = 100           ; Minimum duration of Voice to considered as a word
between_words_silence = 50      ; Minimum duration of silence after a word to consider
                                ; the audio what follows as a new word
maximum_number_of_words = 3     ; Maximum number of words in the greeting.
                                ; If exceeded then MACHINE
silence_threshold = 256

Tips:

• silence_threshold: 這是用來辨識silence的音量基準值，只要偵測到聲音低於這個值，就視為 silence。通常這個值僅可能的低，對於有些手機的用戶，因為手機的噪音會比較大，可能要稍微將它調高。

參考連結

• voip-info: Answering Machine Detect (AMD)
• asterisk-users: How to tune Asterisk AMD - Answering Machine Detection "hacks"