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Why there is initial delay for outbound calls

The initial delay is caused by:

1). Modem/computer delay when playing the audio file

There is little room to improve. This has more to do with audio stream going through the IO bus and to the modem and to the phone line.

2). Live human and answering machine detection.

When the phone is answered, it could be a live person or answering machine. The system needs some time to detect the situation based on collected statistics. This detection requires up to a few (3) seconds.

3). Application delays

If you develop an application based on Voicent Gateway, and your initial VoiceXML file is dynamically generated, there might be delays there too.

The Text-to-speech engine takes some time to generate an audio stream. So it is recommended to convert text to audio offline as much as possible. Voicent Gateway actually pre-generate the initial text to audio before the call is made, so for a single line system, this does not contribute too much time to the initial delay. But for a muti-line system, the text-to-speech will slow down the overall system due to its large computational requirement.

4). Really slow and old computer

Most of today’s computers are fine for Voicent applications, especially for a single line system. For multi-line system, you do need a decent computer. You can use Windows task manager to see whether your computer is using too much CPU and memory during outbound calls. Please also check the FAQ for what type of the system you need.


So in general, there will be 2-3 seconds initial delays. And for most people, the system will start to play the message after he/she says the second hello.

The following is a special situation that you can set to reduce the delays:

If you do not care about answering machine, you can bypass the human vs answering machine detection. So the system can play the message as soon as it recognizes any human voice. The drawback is that the sytem will treat all answering machine as live human pickup, and all answering machine messages will be cut off at the beginning.

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