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Answering Machine Detection

Detect answering machine and live human pickup is based on statistical data. No telephony system today is able to make it 100% accurate. This probably will never be possible. Even humans make mistakes in noisy environment like airport. But for most situations, the detection should work well.

Most call detection problems are related to phone line noise. This is the first place to check. The line noise problem might be caused by both ends of the phone call. For example, if the receiving end is a cell phone and the cell signal is not that strong, the noisy line tends to mislead the human voice detection process. On the modem end, it could be caused by simple things like a really long phone line between the phone jack and the modem.

More information can be found on the Modem and dialing FAQ.

One good tool to help you to hear what the modem “hears” is to use the “Record Initial Dialing” feature of the gateway. You can turn it on by selecting “Help > Record Initial Dialing” from Voicent Gateway’s main menu. After it is turned on, the gateway should record the audio to a .wav file. The gateway records the audio starting from the time it dials till it detects a live person or an answering machine. The rest of the phone call is not recorded.

These wave files can be found under:

C:\Program Files\Voicent\Gateway

They should be named pickup_*.wav. You can click on the file and hear the audio stream. If you hear a lot of background noise, then your detection is not going to be accurate. You should use a phone line with better quality.

If the problem only happens on a few answering machines, you should send the pickup_*.wav files to It will help us improve the detection algorithm.

As a work around, some of our customers simply play the message twice, or repeat the important message for answering machines. For live human pickup, add a replay option at the end.

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