False positives
False positives are humans that were misinterpreted as answering machines, in which case the dialer hangs up the call, or plays the amfile. The main causes of false positives are:
▪The human speaks a long greeting (> max). This typically happens when reaching a business number. If an amfile file is specified, the respondent will hear it.
▪The human has loud background noise (permanently above the db threshold). This typically occurs with car phones. The playback of amfile starts when the AMD algorithm has waited for end-of-greeting for off seconds. However, this timer needs to be longer than the longest AM greeting (~30 seconds), so it is unlikely that the respondent will wait long enough to hear amfile.
Humans can also be misinterpreted as “No audio”. This occurs when:
▪There is no audio connection (for example, because the battery in the respondent's phone is running low). After on seconds without start-of-voice, the dialer hangs up (call outcome: No audio).
▪The human picks up the phone but does not start speaking immediately (for example, the respondent is busy, or due to a disability). After on seconds, the dialer hangs up.
▪The greeting was spoken very softly (below the db threshold). Usually the respondent speaks up louder, but if the voice is not raised the dialer hangs up after on seconds. The dialer plays the amfile to “No audio” numbers unless the setting is disabled by option cp:-S (hangup immediately if silence).
See also