Call Center KPIs: Service Level, First-Call Resolution and What Each Client Really Pays
By PlainSight — Insightful Actions · Updated October 2026 · ~5 min read
An outsourced contact center sells agent time measured against promises: answer this share of calls within so many seconds, resolve them, don't keep people waiting. Miss the promises and the contract pays you less; staff far beyond them and the hours cost more than the client pays. So the business sits between two sets of numbers: the service ones your clients watch, and the money ones only you see. Here are both.
Where your numbers live
Two exports cover it. From your billing or accounting system: invoice lines with the date, the client, the type (support contract, overage minutes, setup, SLA credit) and the amount, credits as negative lines.
From your phone or contact-center platform: the daily or interval report, with calls offered, calls answered within the target, calls abandoned, handle time and agent hours. Agent names aren't needed.
The numbers your clients watch, and the ones only you see
1. Service level, by interval
What good looks like: the target in each contract met interval by interval, not only on the monthly average.
The share of calls answered within a set number of seconds. Answering 80% within 20 seconds is a common target, though contracts vary. A monthly average can hide every Monday morning missed, so measure it in the intervals the contract measures, and staff to the intervals you miss.
2. Abandonment
What good looks like: under 5%, and lowest on the queues that matter most to the client.
Calls where the caller hung up before an answer, divided by calls offered. SQM Group puts the industry standard at 5% to 8% and calls under 5% good. Hang-ups in the first few seconds are usually mistakes (SQM puts them at up to 2% of calls), so set them aside before you judge the queue.
3. First-call resolution
What good looks like: 70% or more, and rising.
The share of issues solved on the first contact, with no repeat contact about the same issue. In SQM Group's benchmarking the average is 71%, 70% to 79% is good, and 80% or more is world-class, reached by about one center in twenty; telecom queues average lower, around 56%. Every repeat call is an hour you pay for twice, and under per-minute billing it can look like revenue while the client counts it as a failure.
4. Occupancy and revenue per agent hour
What good looks like: occupancy high enough to pay for the floor and low enough that agents stay; every client above your cost per agent hour.
Occupancy is the share of logged-in time agents spend handling contacts. Larger teams can run higher occupancy at the same service level, so a small team will sit lower. Then divide each client's revenue by the agent hours that served it. A client whose revenue per agent hour sits below what an hour costs you, wages and overhead included, loses money on every call.
5. SLA credits
What good looks like: rare, and each one traced to a cause.
Credits issued for missed service levels, by client and month. In your invoice export they are the negative lines. One credit is a bad week; credits in consecutive months mean the staffing model or the contract terms don't fit the call pattern, and they cost you twice: the credit now, and the client's confidence before renewal.
6. Agent turnover
What good looks like: lower than last year, and not concentrated in one client's queue.
People who left in the year divided by average headcount. SQM Group puts the industry standard at 30% to 40% a year. Each departure costs recruiting and the weeks before a new agent reaches full speed. Turnover clustered in one queue usually means that client's calls are harder than the contract priced.
7. Client concentration
What good looks like: no client large enough that losing it would empty a floor.
Your biggest client's share of revenue and of agent hours. A large client brings steady volume and a renewal you have to win. Know when each contract comes up, and start the renewal with the service record in hand.
Warning signs worth acting on
- SLA credits two months running for the same client.
- Repeat calls rising while handle time falls — calls closed fast and solved later.
- One queue with most of the turnover.
- Overage minutes billed but never staffed for.
- Any client whose revenue per agent hour is below your cost.
Make it a weekly and monthly rhythm
Weekly: service level by interval, abandonment and repeat calls, client by client. Monthly: revenue per agent hour, SLA credits, turnover and the renewal calendar.
Let PlainSight read your invoice export
Upload an invoice export and PlainSight breaks revenue down by client and line type, shows the SLA credits and how concentrated the book is, and writes the next steps in plain English. Everything runs in your browser — your data never leaves your device.
See it on a live example →
Frequently asked questions
- What file does PlainSight need from a call center?
- An invoice export with a date, the client, the line type (contract, overage, setup, credit) and the amount. SLA credits as negative lines are fine. Interval reports from your phone platform can sit in a second file.
- Why isn't the monthly service level enough?
- Because contracts and callers live in intervals. A good month can hide the same busy hour missed every week, and the callers in that hour are the ones who complain.
- What counts as first-call resolution?
- An issue solved on the first contact, confirmed by no repeat contact about the same issue within a set window, or by the customer saying so in a survey. Pick one definition and keep it, so the trend means something.
- Is my data safe if I use PlainSight?
- Yes. Files are processed entirely in your browser and never uploaded. Optional AI features send only anonymized summary totals, never names or raw rows.
Sources
This guide is general information for contact-center owners and managers, not financial, tax, or legal advice. Figures described as “typical” or “common” are survey results and rules of thumb, not standards — always read your own numbers in context.