Wait For Silence Options: Holding the Message Until the Beep

When a machine answers, the outgoing greeting plays before the beep. If your message starts during that greeting, it talks over the recipient's own announcement and the start of your audio is wasted. Wait For Silence Options tells VICIdial to listen for a stretch of quiet first, which usually means the greeting has finished, before it begins playing your message. It is a lightweight way to land your message after the beep instead of on top of the greeting.

What the field controls

Wait For Silence Options applies to calls detected as answering machines and holds the message until the line goes quiet. The field takes three values separated by commas:

• First value: how long to detect silence, in milliseconds.
• Second value: how many times that silence must be detected before the message plays.
• Third value: the maximum number of seconds to wait before timing out and playing the message anyway.

The default is empty, which leaves the feature disabled. A standard starting value is to wait for two seconds of silence twice, written as 2000,2,30. That means: detect 2000 milliseconds of quiet, require it to happen twice, and give up waiting after 30 seconds. The timeout matters because some greetings never pause cleanly, and without it a call could hang waiting for silence that never comes.

How the wait plays out

flowchart TD
  A[Call detected as machine] --> B[Start listening for silence]
  B --> C{Silence held long enough}
  C -->|Yes| D{Count reached}
  D -->|No| B
  D -->|Yes| E[Play the message]
  C -->|No| F{Timeout reached}
  F -->|No| B
  F -->|Yes| E

VICIdial listens for the first silence window. Each time it counts a qualifying gap, it ticks toward your required count. Once the count is met, the message plays. If the greeting keeps talking past your timeout, the system stops waiting and plays the message anyway so the call is not wasted. This gives some rough machine detection on top of the silence wait, since a live person who picks up and stays quiet briefly will also trigger playback.

How it compares to full detection

Wait For Silence is not the same as full answering machine detection (AMD (answering machine detection)). True detection runs analysis on the audio to classify the answer, while the silence wait simply holds the message until the line is quiet. The silence approach is simpler and avoids some of the processing cost of detection, but it is rougher. You will still miss some of the beginning of a recording on certain machines, and any delay can cause a live customer to hang up before the message starts.

Because of that, record your message twice in the file so a clipped start still plays in full once. This pairs naturally with beep detection (Beep detection) thinking: you want the message to land after the tone, and the doubled recording covers you when the timing is off. Tune the three values against your own lines, since carrier (Carrier) behavior and greeting lengths vary.

Where this fits

Silence-based waiting is one of the lighter ways to time a message drop. For the full picture, read our AMD and CPD guide. To weigh waiting and detection against simply timing the ring, see AMD versus Dial Timeout.

On VICIfast the dialplan edits this kind of timing usually needs are handled for you, so setting Wait For Silence is just a field, not a server task. See VICIfast pricing to get a tuned campaign running.