The math, plainly
How the estimate works
How is calls per hour worked out?
A rep's hour is spent ringing, talking and wrapping up. In power mode, every dial rings for a while; a share of dials (the connect rate) turn into a conversation, which takes the talk time plus the wrap-up. So one dial takes, on average, ring time + connect rate × (talk time + wrap-up), and an hour holds 3,600 seconds divided by that.
In parallel mode, several lines ring at once and the rep takes the first person who answers. With L lines and connect rate c, the chance that at least one answers is 1 − (1 − c)^L. Each batch costs one ring time plus, when someone answers, one conversation. Dials go up L times per batch; conversations go up by the chance of an answer.
The model leaves out the seconds between calls and the time it takes to confirm a person rather than a voicemail. Real numbers will be a little lower for both modes.
When does parallel dialing help most?
When few people answer. At a 5% connect rate, a rep in power mode spends most of the hour listening to rings, and three lines nearly triple the chances of a conversation per batch. At a 50% connect rate, one line already reaches someone every other dial; extra lines add little and drop more answers.
Try your own numbers: drag the connect rate and watch the gap between the two cards open and close.
What's the 3% abandoned-call rule?
Under the FTC's Telemarketing Sales Rule, a call is abandoned if the person who answers isn't connected to a rep within two seconds of their greeting. Telemarketers calling consumers stay in the rule's safe harbor only if abandoned calls are no more than 3% of calls answered by a person, per campaign, measured over 30 days (or the campaign, if shorter). They must also let unanswered calls ring for at least 15 seconds or four rings, play a recorded message naming the seller and a callback number to anyone they can't connect, and keep records. The FCC has a matching 3% rule for telemarketing calls.
In parallel dialing, the person who answers second in a batch may not get a rep. The calculator's worst case counts every extra answer as dropped, so treat its abandon rate as a ceiling. Most business-to-business calls fall outside the TSR, but consumer lists are squarely inside it.
How TopReach's parallel dialer handles it
TopReach's parallel dialer starts each run at 3 lines, lets reps move a slider up to the workspace ceiling (10 by default; an admin can set up to 20), and rings each unanswered line for 25 seconds by default.
When someone answers, the other lines keep ringing for about 3 seconds while the dialer confirms it's a person, then stop. Anyone who answers and can't be connected hears a short message with your business name and a callback number, and lines that were canceled before anyone picked up ring again later. Abandoned pickups are counted in reporting, so you can keep consumer lists under 3%.
Parallel and power dialing are both included in the $99 a month phone license, with local presence and 3,000 calling minutes.
