AMDY.IO
Start free
← All articles
Product UpdatesAug 21, 2026 9 min read

How to Set Up Voicemail Drop in ViciDial: A 2026 Configuration Guide

Voicemail drop saves your agents time. But it only works when your AMD engine correctly identifies voicemail in the first place. If your detection is wrong 20% of the time, you're dropping messages on live humans and hanging up on real leads. That's the problem this guide addresses alongside the setup steps.

Below you'll find a complete ViciDial voicemail drop configuration walkthrough, the AMD settings that control it, and why detection accuracy is the variable that determines whether this feature helps or hurts your operation.

What Voicemail Drop Actually Does in ViciDial

Voicemail drop lets ViciDial automatically play a pre-recorded audio message when the AMD engine detects a voicemail greeting. The agent never hears the beep. The system plays the message and moves on. Your agents stay on live calls.

Done right, voicemail drop increases agent talk time per hour and keeps your team focused on conversations that can close. Done wrong — with a poorly tuned AMD engine underneath it — it plays your pre-recorded message to a live human who just said "hello," then hangs up. That's a burned lead, a ghost call complaint, and a potential TCPA exposure.

The configuration below assumes you're running ViciDial on Asterisk. The same logic applies to GoAutoDial and FreePBX.

Prerequisites Before You Configure

Before touching any settings, confirm these are in place:

  • ViciDial is running and your campaign is active
  • AMD is enabled in your ViciDial server settings (more on this below)
  • A pre-recorded voicemail message is uploaded as a .wav or .gsm file, mono, 8kHz, 16-bit
  • You have admin access to the ViciDial Admin panel

Audio file quality matters more than most guides acknowledge. ViciDial plays the file exactly as recorded. A noisy or clipped recording sounds unprofessional and reduces callback rates.

Step 1: Upload Your Voicemail Drop Audio File

  1. Log in to the ViciDial Admin panel
  2. Navigate to Admin > Audio Store
  3. Click Add New Recording
  4. Upload your .wav file and give it a clear name (e.g., vm_drop_insurance_july2026)
  5. Save the file and note the filename — you'll reference it in campaign settings

Keep your message under 30 seconds. Shorter messages get played in full more often because some voicemail systems cut off longer recordings.

Step 2: Enable AMD in ViciDial Server Settings

Voicemail drop depends entirely on AMD to trigger. If AMD is off or misconfigured, the system won't know when to play the file.

  1. Go to Admin > Servers
  2. Select your active server
  3. Find the Answering Machine Detection section
  4. Set answering_machine_detection to Y
  5. Set AMD_action to VMAIL_ONLY if you want AMD to handle voicemail detection only (recommended for most outbound campaigns)
  6. Save changes

ViciDial's built-in AMD uses silence-based detection. It analyzes pause length after the initial audio to guess whether a human or machine answered. Under real-world conditions, that approach produces roughly 80% accuracy. The 20% error rate is what causes live humans to receive your voicemail drop message and get disconnected.

Step 3: Configure Voicemail Drop at the Campaign Level

  1. Go to Admin > Campaigns
  2. Select the campaign you're configuring
  3. Scroll to the Answering Machine section
  4. Set AM_Message to the filename of your uploaded audio (e.g., vm_drop_insurance_july2026)
  5. Set AM_Xfer_Type to VMAIL — this tells ViciDial to play the message and hang up when AMD detects voicemail
  6. Set AM_Message_Exten if you're routing to a specific Asterisk extension for playback (optional, depends on your dialplan)
  7. Save the campaign

From here, when AMD detects a voicemail, ViciDial plays your recorded message and releases the line. The agent never touches it.

Step 4: Test the Configuration

Before going live, test against a real voicemail box.

  1. Place a test call to a number you control
  2. Let it go to voicemail
  3. Confirm the system plays the correct audio file
  4. Confirm the call terminates cleanly after playback
  5. Check your ViciDial logs for AMD: MACHINE detection events

Also test against a live answer. Have someone pick up and confirm the system routes to an agent — not to the voicemail drop message. This is where AMD accuracy becomes visible. If AMD misidentifies the live answer as a machine, your agent gets nothing and the contact hears your voicemail recording before getting disconnected.

Step 5: Monitor AMD Accuracy in Your Reports

ViciDial logs AMD outcomes in the call log. Pull a report filtered by AMD status after your first live session.

Look for:

  • AMD: MACHINE calls where voicemail drop played
  • AMD: HUMAN calls that connected to agents
  • AMD: NOTSURE calls, which ViciDial typically routes to agents by default

A healthy operation shows AMD: MACHINE rates consistent with the expected voicemail percentage for that list. If you're seeing AMD: MACHINE on 30 to 40% of calls on a fresh list, your AMD engine is misclassifying live answers. Those are false positives burning real leads.

The AMD Accuracy Problem That Breaks Voicemail Drop

Here's the part most ViciDial guides skip.

Voicemail drop configuration is straightforward. The AMD engine underneath it is not. ViciDial's native silence-based AMD was built for a narrower range of audio conditions than what modern outbound calling produces. Carrier variations, regional greeting patterns, and mobile voicemail behaviors all affect detection accuracy in ways silence thresholds can't reliably handle.

At 80% accuracy, 1 in 5 live humans gets misclassified as a machine. Your voicemail drop plays. They hear a pre-recorded message, get confused, and hang up. Lead gone. At scale, a 10-agent team loses an estimated $24,000 per month to AMD false positives.

This is why the voicemail drop feature and the AMD engine are inseparable. The configuration above sets up the feature correctly. Whether it performs correctly depends entirely on what's doing the detection.

AMDY.IO replaces ViciDial's native AMD with a machine learning engine that analyzes audio fingerprints in real time. It achieves 99% accuracy distinguishing live humans from voicemail. It installs into ViciDial with a one-line command. Your voicemail drop logic stays exactly as configured above. The detection underneath it becomes significantly more reliable.

Common Voicemail Drop Errors and Fixes

Voicemail drop plays on live answers

Cause: AMD false positive. The engine classified a live human as a machine.

Fix: Audit your AMD settings. If you're running native ViciDial AMD, review your silence threshold and initial silence values. The better long-term fix is replacing the detection engine with one built for current carrier behavior.

Audio file doesn't play

Cause: Wrong filename in AM_Message, or an incompatible file format.

Fix: Confirm the filename matches exactly (case-sensitive). Re-encode the file as mono .wav, 8kHz, 16-bit using SoX or Audacity.

Call doesn't terminate after voicemail drop

Cause: AM_Xfer_Type is misconfigured, or the Asterisk dialplan isn't handling the hangup correctly.

Fix: Verify AM_Xfer_Type is set to VMAIL and that your dialplan includes a Hangup() application after the Playback() command.

AMD: NOTSURE events are high

Cause: The AMD engine can't confidently classify the call. Common with certain mobile carriers and regional voicemail greetings.

Fix: Configure how ViciDial handles NOTSURE events. Most operations route them to agents to avoid losing live connections. If NOTSURE rates stay consistently high, the detection engine needs to be replaced.

Voicemail Drop and Compliance

Voicemail drop sits in a compliance gray zone in several jurisdictions. In the US, the TCPA governs automated calls and pre-recorded messages. Dropping a pre-recorded voicemail to a consumer without prior express written consent can expose your operation to liability.

This applies whether the call is answered live or goes to voicemail. The key distinction is whether the recipient is a consumer (B2C) or a business contact (B2B). B2B voicemail drops carry less regulatory risk, but verify with legal counsel for your specific use case and state.

Ghost calls create a separate compliance problem. They occur when AMD misclassifies a live answer and the system hangs up without playing anything. Ofcom's silent call rules in the UK and FCC guidance in the US both flag repeated ghost calls as violations. Accurate AMD detection eliminates ghost calls at the source.

Frequently Asked Questions

What file format does ViciDial require for voicemail drop audio?

ViciDial requires mono .wav or .gsm files encoded at 8kHz, 16-bit. Files encoded at higher sample rates or in stereo will either fail to play or sound distorted. Re-encode using SoX with: sox input.wav -r 8000 -c 1 -b 16 output.wav

Can I use different voicemail drop messages for different campaigns?

Yes. Each campaign has its own AM_Message field. Upload multiple audio files to the Audio Store and assign them independently per campaign. This lets you run separate messages for different verticals or call lists at the same time.

Why is my AMD: MACHINE rate unusually high?

If AMD: MACHINE events exceed your expected voicemail rate for a given list, the AMD engine is producing false positives. ViciDial's native silence-based detection is sensitive to carrier variations and mobile voicemail greeting lengths. High false positive rates mean live humans are receiving your voicemail drop message and being disconnected.

Does voicemail drop work with predictive dialing in ViciDial?

Yes. Voicemail drop is fully compatible with ViciDial's predictive dialing mode. When AMD detects a machine during a predictive dial, the system plays the configured message and releases the line, keeping agents available for live connections.

How does AMD accuracy affect voicemail drop performance?

Directly. At 80% accuracy, 20% of voicemail drop triggers fire on live humans. At 99% accuracy, that error rate drops to 1%. The difference at scale is substantial — a 10-agent team can lose an estimated $24,000 per month to AMD false positives.

Is voicemail drop legal for consumer outbound campaigns?

It depends on jurisdiction and consent status. In the US, the TCPA requires prior express written consent for pre-recorded messages delivered to consumers. B2B campaigns carry less risk but aren't exempt in all states. Consult legal counsel for your specific campaign type before deploying voicemail drop at scale.

Can I replace ViciDial's native AMD without changing my dialplan?

Yes. AMDY.IO installs into ViciDial with a one-line command and replaces the native AMD engine without requiring dialplan changes. Your voicemail drop configuration, campaign settings, and call routing stay intact.

Get More Out of Every Voicemail Drop

Voicemail drop takes minutes to configure. Getting it to perform reliably requires accurate AMD underneath it.

If your ViciDial AMD is producing false positives, every misclassified live answer is a lead you paid for and threw away. At 15 to 20% false positive rates, that cost compounds fast.

Start a 14-day free AMD trial at amdy.io and see the accuracy difference on your own call volume. No setup fees. One-line install. Same-day deployment.