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AI Dialer

Glossary · Dialing

What is Parallel dialing?

  • Also called: multi-line dialer

Reviewed by Sujan ThapaliyaLast updated

Definition

Parallel dialling places several calls at once for one rep and connects the first human answer, dropping the rest. On lists where most calls go unanswered it produces several times more live conversations per hour than dialling one at a time.
The three STIR/SHAKEN attestation levels, which underpin how parallel dialing behaves in practice: A asserts both that the carrier knows the customer and that the customer may use the calling number, B asserts the customer only, and C asserts neither. A shared number pool can reach B at best, which is why number ownership keeps recurring in these definitions.
Attestation is the backdrop to most caller-ID and deliverability terms, parallel dialing included.

In practice

How parallel dialing actually works

The difference from predictive dialling is who the lines belong to. Parallel lines belong to one named rep; predictive dialling forecasts across a pool of agents.

Connect latency is the whole game. If the bridge takes longer than about half a second after 'hello', the prospect hears the pause, knows they were auto-dialled, and the call is effectively over.

The mode also concentrates risk in a way power dialing does not. Every abandoned call is a complaint waiting to be filed, and complaints attach to the number rather than the campaign — so a fortnight of aggressive line counts can leave a number labelled long after the campaign that caused it has ended.

Worked example

At a 6% answer rate, 4 lines produce roughly one live conversation every four dial cycles instead of one in seventeen.

Parallel dialing: common questions

How many lines should a parallel dialer run?
Three is a common starting point. The right number is set by your list's answer rate: a list answering at 3% supports more lines than one answering at 20%, because the chance of two humans answering at once is what determines the risk.
What happens when two people answer at the same time?
One is connected to the rep and the other is dropped, which counts as an abandoned call. That is the central cost of parallel dialing, and it is why line count has to be set from the real answer rate rather than from ambition.
Does parallel dialing damage number reputation?
It can. High dial volume with a low connect rate and very short average duration is precisely the pattern carrier analytics score as unwanted calling. Spreading volume across owned numbers with daily caps is what keeps it survivable.

Sources

  1. Combating Spoofed Robocalls with Caller ID Authentication — Federal Communications CommissionThe STIR/SHAKEN framework, the attestation levels carriers sign calls with, and the mandate requiring providers to authenticate caller ID.
  2. 47 U.S.C. § 227 — Restrictions on the use of telephone equipment — Cornell Legal Information InstituteThe Telephone Consumer Protection Act itself — the consent requirements, calling-hours limits, and private right of action.
  3. ITU-T Recommendation E.164 — The international public telecommunication numbering plan — International Telecommunication UnionThe international number format, the 15-digit maximum, and how country codes and national numbers compose.

See parallel dialing in the product

A parallel dialer places several outbound calls at once for a single rep and connects the first one a human answers, dropping the rest. Because most cold calls go unanswered, dialling three to five lines in parallel produces several times as many live conversations per hour as one-at-a-time dialling.

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