Self-Sizing Number Pools
Pay for the tracking numbers your traffic uses, not the ones your peak needs
Lead Router leases a tracking number to each visitor session, returns it when the session ends, decays idle numbers, releases unused ones before renewal and buys more only on demand. Rent follows your concurrency, not your busiest hour.
How it works
- 1
Lease a number per session
When a visitor lands, the script asks the pool for a number and holds it for that session: ten minutes of idle time and thirty minutes overall by default, with a five-minute grace period after the browser closes so a call placed on the way out still matches. Both limits are configurable up to four hours.
- 2
Sweep every hour
Expired leases return their numbers to the pool. Numbers a campaign bought that have sat idle for the configured number of days decay back to your shared pool, and any campaign with a floor of spare numbers is topped back up to it. The sweep runs decay before replenish, so a campaign never decays a number and buys it back in the same pass.
- 3
Release before renewal
Each number renews on a thirty-day cycle. A shared number with no live call that is about to renew is released to the carrier instead, and the rent stops. A number bought during a spike therefore costs at most one extra renewal.
Estimate your monthly number rent
Your busiest hour — the size a fixed pool has to be
An ordinary hour — what a self-sizing pool floats near
The floor the hourly sweep never decays below
At the current published rate of $1.50 per number / month
Fixed pool, sized for the peak
$60.00/mo
40 numbers
Self-sizing pool
$15.00/mo
10 numbers
You keep
$45.00/mo
$540.00/yr
A spike adds numbers for at most one renewal each; idle numbers decay back and unused ones are released before they renew.
Why a fixed pool costs more than it should
A pool sized by hand has to be sized for the busiest hour, and then it is billed every month at that size.
Rent follows the peak
A number is only busy while the session holding it is live, so the pool you need is set by how many visitors are on the page at once, not by monthly traffic. A fixed pool sized for the peak hour rents that many numbers around the clock.
Spikes become permanent
A campaign launch or a viral day forces the pool up. With manual sizing nobody sizes it back down, and the extra numbers renew month after month.
Idle numbers hide in plain sight
Numbers a paused campaign no longer uses keep renewing unless someone notices. Each one is small; a portfolio of them is not.
The alternative is not a smaller pool
Under-sizing a fixed pool means visitors arrive when every number is leased. Lead Router shows the campaign's primary number instead and records that session as unattributed, so a pool miss is visible rather than guessed. The fix is a pool that grows on demand, not a bigger fixed one.
How the pool sizes itself
Four mechanisms, all automatic, each with a setting behind it.
Per-session leases
A number belongs to one visitor session at a time and is back in the pool when that session ends. Concurrency, not traffic, decides how many numbers are out.
A floor of spare numbers
Set how many numbers a campaign keeps ready. The hourly sweep tops the floor back up and never decays below it, so a quiet campaign holds its reserve without traffic.
Auto-buy on demand
When every number is leased and the campaign is below its maximum pool size, the pool buys another number rather than turning a visitor away, within a daily purchase limit. New numbers show as provisioning until the carrier confirms them.
Idle decay
A number a campaign bought that has had no session for the configured number of days — seven by default, adjustable per campaign from zero to ninety — returns to your shared pool, where any campaign can lease it.
Release before renewal
A shared number with no live call that is within the release window of its next renewal is released to the carrier. Rent for that number stops with that renewal.
Late callbacks still route
A released number remembers the campaign that last held it for twenty-four hours, so a caller who saved the number and rings back after the session ended still reaches the right routing.
Estimate your rent
The estimator at the top of this page uses the current published rate per number and three figures you already know.
Peak visitors holding a number
Your busiest hour. A fixed pool must be at least this size, and it is billed at that size every month.
Typical visitors holding a number
An ordinary hour. A self-sizing pool floats near this figure plus the floor you keep.
What the arithmetic assumes
The estimate compares a fixed pool sized for the peak with a self-sizing pool that settles at your typical concurrency plus the floor. A spike adds numbers for at most one renewal each; the estimate does not count them, so a month with a spike lands between the two figures.
What you control, and what the platform handles
Every mechanism above has a setting, and every default is chosen so that doing nothing is safe.
Lease length
Idle minutes and maximum minutes per session, and the grace period after the browser closes.
Floor and ceiling
The spare numbers a campaign keeps ready and the maximum pool size auto-buy may reach. A daily purchase limit applies platform-wide.
Idle decay days
A platform default, an account-level override, and a per-campaign override. Zero means a campaign's numbers never decay.
Release window
The platform releases an unused shared number a few days before its renewal. Every purchase, decay and release is written to the audit log, so the pool never changes size silently.
What your account needs
Calls and dynamic number insertion enabled on your account, a campaign with DNI turned on and auto-buy enabled with a maximum pool size, and the DNI script on the page you are tracking. Pool settings live under System → Call Settings → Number Pool and on each campaign's DNI panel.
Frequently asked questions
What happens when every number in the pool is leased?
The page shows the campaign's primary number and that session is recorded as unattributed. With auto-buy enabled and room under the maximum pool size, the pool buys another number so the next visitor gets one of their own.
If a number is released, does a caller who saved it reach a dead line?
Not within twenty-four hours of release. The number keeps a pointer to the campaign that last held it, and a callback in that window routes as that campaign's call.
How quickly does a pool grow?
One number at a time, when a visitor arrives and every number is leased, up to the campaign's maximum pool size and within the daily purchase limit. Newly bought numbers show as provisioning until the carrier confirms them.
Is there a minimum pool?
Only if you set one. A floor of spare numbers keeps a campaign ready for its first visitor of the day; the sweep replenishes it and never decays below it.
Am I charged for a number that was released mid-cycle?
Numbers are billed per thirty-day renewal. A number released before its next renewal is not renewed, so the cycle already paid is the last rent for that number.
Where does the rate on this page come from?
From the same published tracking-number rate as the pricing page. It is read live, so a rate change appears here without a deploy.
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