Why VICIdial AMD Misses Machines and Sends Them to Agents

A false negative is when answering machine detection (AMD (answering machine detection)) lets a machine through as if it were a person. The call lands on an agent (Agent), who listens to a voicemail greeting, waits for the beep, and burns time they should have spent on a live answer (Live answer). A few of these per agent per hour adds up fast. Here is why AMD misses machines and how to tighten it.

Why machines slip through

Modern voicemail greetings are short and natural. A cell greeting that says "hey, leave a message" sounds almost exactly like a person answering. When the recorded greeting is brief and the speech pattern is human, AMD does not have enough to work with and defaults to treating the call as a person. The detection is built to err toward sending calls to agents, so when it is unsure, machines win.

Carrier (Carrier) behavior makes it harder. Some lines connect the call before the greeting even starts, so AMD hears silence first and then a short message and never gets a clean signal. The result is that machines reach agents and your contact data gets a status (Status (lead status)) that says a person answered when none did.

flowchart TD
  A[Machine answers with short greeting] --> B[AMD hears brief speech]
  B --> C{Enough signal to call it a machine}
  C -->|No| D[Defaults to HUMAN]
  C -->|Yes| E[Flagged as MACHINE]
  D --> F[Sent to agent]
  F --> G[Agent stuck on voicemail]
  E --> H[Hang up or play message]

Measure how often it happens

Pull the AMD Log Report and check how many answered calls were sent to agents as humans. Then ask your agents how many voicemails they are hitting, or listen to a sample of recordings. If lots of agent-routed calls were machines, you have a false-negative problem. The AMD Log Report guide walks through reading the results.

Tighten detection to catch more machines

Fixing false negatives means making AMD quicker to call something a machine. In the AMD Asterisk parameters, that usually means treating shorter greetings as machine-like and reducing how much benefit of the doubt a call gets before it is classified. The trade-off cuts the other way from false positives: tighten too far and you start flagging real people as machines. Adjust one parameter at a time and watch the log after each change. The detail is in our guide to the AMD Asterisk parameters.

Routing helps too. By default, calls AMD marks NOTSURE go to agents, which is safe for live answers but lets ambiguous machines through. If false negatives dominate, you can change how NOTSURE calls are handled so fewer uncertain calls reach agents. Just remember that every NOTSURE you divert is a small risk of cutting a real person.

Know the limits of AMD

The built-in detection cannot catch every machine, especially short cell greetings. It also adds processing time to every call regardless of outcome. For some campaign (Campaign) types, a tuned Dial Timeout around 22 to 26 seconds avoids more voicemails than aggressive detection without slowing live calls. Weigh both in the AMD and CPD complete guide and the comparison of when to use VICIdial AMD.

Keeping machines off your agents is steady work, and a clean dialer setup makes it far simpler. VICIfast manages the AMD application and routing so you can tighten detection from the campaign screen and check results in the log. See VICIfast pricing to get a managed dialer that keeps agents on real calls.