What Is Grade of Service (GoS) in VICIdial?

Grade of Service, shown as GoS in VICIdial's forecasting reports, is one of those terms that sounds like a quality score but actually means the opposite of good news. It is the probability that a call is dropped before an agent gets to it. Lower is better. This post explains what it measures and how it decides how many agents you need.

GoS lives in the forecasting corner of the reports menu, which the VICIdial reports guide lays out in full.

The plain definition

Grade of Service is the chance that a given inbound call is dropped at a particular staffing level. If your GoS target is 0.03, you are saying you will accept 3 out of every 100 callers being lost rather than reaching an Agent. The report treats GoS as your desired drop rate and works backward to a recommended agent count.

It is closely related to, but not the same as, your Abandonment rate. Abandonment is what already happened, measured after the fact from your call records. GoS is the target probability you are designing your staffing around before the calls arrive. You can think of GoS as the abandonment rate you are aiming to never exceed.

In VICIdial's forecasting reports GoS shows up as a column for each hourly interval, and you also supply it as the desired drop rate when you set the report up. The report then has two jobs: show you the drop probability the math predicts, and use your target to recommend how many agents you would need to meet it.

How GoS drives staffing

The report already knows the traffic load for each hour as a number of Erlangs. You hand it a target GoS. It then tries agent counts until it finds the smallest number of agents where the drop probability falls to your target or below. That number becomes Rec Agents, the recommended agent count for the hour.

flowchart TD
  A[Traffic load in Erlangs] --> C[Test an agent count]
  B[Target GoS] --> C
  C --> D{Drop chance at or below target}
  D -->|No| E[Add one agent]
  E --> C
  D -->|Yes| F[Rec Agents found]

This is why a tighter GoS costs more bodies. Going from a 5% to a 1% target on the same traffic can mean several extra agents per hour, because each additional point of reliability gets harder and more expensive to buy. The curve is steep at the strict end, so it pays to know whether your callers actually need a 1% target or whether 3% is fine.

Picking a sensible target

• Sales lines often accept a looser GoS, since a missed call can be re-contacted.
• Support or compliance-sensitive lines usually want a tight GoS, because a dropped caller is a real cost.
• Match GoS to the promise you make about your Service level. There is no point staffing for 1% drops if your SLA only requires 5%.

GoS in context

GoS is one lever; agent count is the other. Once you set the target you can read Rec Agents straight down the hourly rows and build a roster. For the daily service-level view that pairs nicely with this, see the inclusive SLA per day report.

Treat GoS as a deliberate business choice, not a leftover default. If you want a hosted VICIdial that has these forecasting tools ready out of the box, see VICIfast pricing.