How a dialer decides how many calls to launch

August 26, 20264 min read

Pacing is the most important decision a dialer makes: how many calls to launch per available agent. Too few and people wait; too many and calls get dropped.

The pacing problem

If an agent becomes free and the dialer launches one call, chances are nobody answers: between voicemails, bad numbers and people who do not pick up, most attempts never become a conversation. The agent waits.

If it launches five, two will probably answer and there is only one agent. The second call gets dropped: that is abandonment, and it has a legal cap.

How it is calculated

The dialer measures, in short windows, what share of launched calls ends in conversation. From that it estimates how many it needs to keep every agent busy:

calls_to_launch = free_agents / contact_rate

# With 10 free agents and a 20% contact rate:
#   10 / 0.20 = 50 calls

The formula is simple. The hard part is that the contact rate changes: it is not the same at 10 in the morning as at 7 in the evening, nor in a fresh list as in one worked for three months.

The control loop

That is why pacing is not a fixed number but a loop that corrects itself:

• If abandonment is below target, it ramps the rate up gradually.
• If it goes over, it cuts sharply and ramps back up slowly.

Ramping up slowly and cutting fast is deliberate. Running a bit slower for a few minutes costs a few contacts; going over the legal limit costs far more.

Where it breaks: the denominator

The whole loop depends on measuring abandonment correctly, and that is where the most common mistake lives:

Only a call where someone picked up can be abandoned. Including calls that rang unanswered puts calls into the math that could never have been abandoned.

The three numbers to watch

1. Abandonment, measured against answered calls and against the phone system CDR.
2. Agent occupancy: what share of the shift is spent in conversation. Under 40% the pacing is too conservative.
3. Wait time between calls: if it climbs, the loop is over-braking.

When pacing is not the problem

Before tuning the rate, check two things:

• If 15% of answered calls are voicemail, speeding up only delivers more voicemails per hour. First remove the voicemails.
• If your real contact rate is 4%, no pacing fixes that: the problem is the data. Measure properly first.

Frequently asked questions

What is dialer pacing?

It is the decision of how many calls to launch per available agent. It is calculated by dividing free agents by the observed contact rate, and it is continuously corrected based on abandonment.

Why does pacing ramp up slowly and cut fast?

Because the costs are asymmetric: running slightly slower for a few minutes costs a few contacts, while going over the legal abandonment limit costs far more.

What is abandonment calculated against?

Against answered calls. Only a call where someone picked up can be abandoned; using launched calls or calls that rang gives the wrong number.