What does concurrent capacity mean for an outbound voice campaign?

Concurrency is the number of calls your system can hold on the wire at the same moment, not the number you make in a day. It is the metric that actually breaks campaigns, because everyone plans in dials per day and then discovers that those dials are not spread evenly. A dial ties up a line for the whole time it rings, the whole time it sits in voicemail, and the whole conversation if a human answers. Add those seconds up across a bursty schedule and the peak is far higher than the daily average suggests. This calculator converts your daily target into a peak concurrent-line requirement, because that is the number your telephony backbone, your LLM rate limits, and your platform have to survive.

How does the calculator turn dials per day into concurrent lines?

It works out how many seconds each dial occupies a line, then spreads the total across your working window and applies a burst factor. A dial that reaches a human holds the line for the full talk time. A dial that hits voicemail holds it for a few seconds under aggressive AMD, or the full message under no AMD. A dial that never answers holds it for the ring window, about 22 seconds. Sum those weighted seconds across your daily volume, divide by your working seconds per day, and you get the average lines in use. Real campaigns are not uniform, so it multiplies by 1.6 to size for the busy hour rather than the daily mean. Sizing for the average guarantees dropped calls at peak.

What is AMD and why does the strategy change my numbers so much?

AMD is answering machine detection, the logic that decides whether a human or a voicemail greeting picked up. Aggressive AMD cuts machine calls in a few seconds so your lines free up fast and your agents only ever talk to humans, but it false-drops a slice of real people who pause before speaking. Balanced AMD keeps most of those humans and filters most machines. No AMD connects everything and lets the agent handle voicemails, which wastes the most minutes but never drops a live person. Each choice shifts three things at once: your usable connect rate, how long lines stay busy, and therefore how many concurrent lines and phone numbers you need. There is no free option, only the tradeoff that fits your offer.

Why does the tool tell me to rotate multiple phone numbers?

Because carriers score outbound numbers on behavior, and a single number pushing hundreds of dials a day gets flagged spam-likely fast. Once that label lands, your answer rate collapses and no amount of concurrency fixes it. The practical ceiling is roughly 50 to 75 dials per number per day before reputation degrades, so the tool divides your volume across a pool and tells you how many local-presence numbers to provision. This is a reputation problem, not a throughput problem, and it is the one most new agencies miss until their connect rate quietly halves. Number rotation, sane per-number caps, and clean A2P registration are what keep a campaign answerable over weeks rather than days.

How does A2P 10DLC registration fit into an outbound voice campaign?

A2P 10DLC governs application-to-person messaging on standard 10-digit numbers, so it applies the moment your campaign sends SMS follow-ups, reminders, or opt-in confirmations alongside the calls. You register one brand for the business and then a campaign per use case, appointment reminders and lead follow-up being separate campaigns with their own approved throughput. Voice calls themselves ride caller-ID reputation and STIR/SHAKEN attestation rather than 10DLC, but nearly every serious outbound operation pairs calls with texts, so both registrations matter. The tool flags the brand-plus-campaign structure you will need. On Hermes the registration and per-number caps are handled inside the platform rather than stitched across Twilio and a separate compliance vendor.

How do I turn this capacity plan into a real Hermes cost?

Take the connected minutes per month the tool estimates and read it against the included minutes on each plan. Starter is 149 dollars a month with 300 included minutes, Business is 399 with 1,000, Agency is 699 with 2,000, and overage is 0.24 dollars per minute on every plan. Outbound campaigns burn minutes fast, so most operators running real volume land on Business or Agency and treat overage as variable cost of goods against the retainer they charge the client. The number that matters is margin per client, not the sticker plan price. Book a walkthrough and we will size concurrency, the number pool, and the plan against your actual campaign rather than a default.

free tool

Outbound dialer capacity calculator.

Put in your daily dials, call length, and AMD strategy. See the concurrent lines you actually need at peak, your live connect rate, how many phone numbers to rotate, and the monthly minutes it burns.

/ target dials per dayTotal attempts across the whole campaign, not per agent or per number./ average talk time (seconds)How long a connected human conversation runs. A qualifying call is 60 to 180 seconds./ dialing window (hours per day)The compliant calling window you actually dial in. Most B2C runs 8 to 9 hours local./ AMD strategyDefault. Keeps most humans, filters most machines. A small false-drop rate.

/ what you need

Concurrent lines at peak

4

About 2.5 on average, sized up 1.6× for the busy hour.

Live human connects per day

300

15% usable connect rate on this AMD strategy.

Phone numbers to rotate

34

Capped near 60 dials per number per day to stay off the spam-likely list. Register one A2P brand plus a campaign per use case.

Connected minutes per month

13,200 min

Talk minutes only, across 22 calling days. Ring and voicemail time is not billed.

Hermes Pro + overage

Custom

Past 2,000 monthly minutes, pricing is custom on Pro.

Book a 20-min walkthrough to cut this number, and we will size concurrency and your number pool with you on the call.

Book a 20-min walkthrough

how it works

Capacity is a peak, not an average.

Almost every outbound campaign is planned in dials per day and then breaks on concurrency. Those two numbers are not the same thing. A dial does not consume a line for a day, it consumes one for the seconds it spends ringing, sitting in voicemail, or talking to a human. Add those seconds up across a schedule that is never uniform, and the busy hour needs far more lines than the daily average implies. Size for the average and you drop calls exactly when your list is most responsive.

The model here is deliberately simple and honest about the tradeoffs. Each dial is weighted by outcome: full talk time for a human, a few seconds for a machine under aggressive AMD or the full message under no AMD, and a ring window for no-answer. That weighted total, spread across your working window and multiplied by a burst factor, is your peak concurrent-line requirement. Change the AMD strategy and watch three numbers move together, because usable connect rate, line-busy time, and number pool all depend on it. There is no setting that wins on every axis.

The phone-number line is the one new agencies skip. Carriers score numbers on behavior, and a single line pushing hundreds of dials a day gets tagged spam-likely, at which point your answer rate quietly collapses. The fix is a rotated pool capped near 50 to 75 dials per number per day, plus clean A2P registration for the SMS that rides alongside the calls. On Hermes the number pool, the per-number caps, and the A2P brand and campaign structure live inside one platform from $149 a month, instead of stitched across Twilio, a dialer, and a separate compliance vendor.

frequently asked

Common questions.

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Outbound dialer capacity calculator.

Capacity is a peak, not an average.

Common questions.

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