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Website number pool

Understand website pool warnings and decide when your site needs more tracking numbers.

If you see Not enough website numbers in NMC (or receive an email with that subject), more visitors browsed your website at the same time than your current pool of tracking numbers could assign individually. When that happens, two visitors temporarily see the same number, which means a call could be matched to the wrong browsing session.

How to handle a pool warning

Section titled “How to handle a pool warning”
  1. Choose Add numbers on the problem banner to jump straight to your website tracking source’s Numbers section.
  2. Check whether your traffic has grown steadily or a new ad campaign is sending more visitors at once.
  3. If your regular traffic outgrew the pool: Choose Add numbers, review the quote, make sure your balance covers the new numbers, and confirm Start tracking.
  4. If it was a one-time traffic spike: Choose Keep {N} numbers (such as Keep 4 numbers) to leave your pool size unchanged. That clears the problem, and NMC will only alert you again if visitors share numbers after a full calendar day passes with zero sharing.

How pool sizing works

Section titled “How pool sizing works”

New website tracking sources start with 4 to 30 tracking numbers, and you can add more anytime up to 30 numbers total:

  • Because NMC holds each assigned number until 30 minutes after a visitor’s latest page view, each number comfortably covers roughly two visitors per hour.
  • Pool size depends on simultaneous browsing sessions rather than simultaneous phone calls. When someone dials a pool number, NMC links the call to whichever visitor was most recently shown that number over the past 90 days. See website numbers.

Pool warnings never stop calls from ringing

Section titled “Pool warnings never stop calls from ringing”

A pool warning only affects visitor-level attribution when traffic peaks; calls to your pool numbers still ring through normally. By contrast, if callers hear a busy signal, check whether your plan stopped running or your balance reached $0 in Paused tracking.

Never copy a number displayed on your website onto print ads, business cards, or online directories; create a separate tracking number for offline or directory sources instead.