Dynamic Number Insertion (DNI) shows each website visitor a tracking number, so Nimbata can tie every call to the source, campaign and keyword that brought the visitor in. This page explains how DNI works and walks you through the full setup, from your first tracking number to a published script.

What DNI is

Tip

To set up your Dynamic Number Insertion (DNI) script, follow Set up DNI step by step.

How DNI works

  • Dynamic Number Insertion (DNI) is a JavaScript script you install once on your website.
  • When a visitor lands, Nimbata shows them a tracking number from your pool. Numbers are served in rotation (round-robin), so the pool never runs out, and a number is not reserved for one visitor: other visitors can be shown it too.
  • That number replaces your regular business number while they browse.
  • Nimbata remembers it in the visitor’s browser for the Max storage days period (21 days by default), so a returning visitor sees the same number. The settings below decide when they are assigned a number again.
  • Nimbata can attribute each call to the exact source, campaign, keyword, and landing page that brought the visitor in.

What changes the number a visitor sees

These settings are in TrackingTracking Code, under Call Tracking. A visitor who browses from page to page on your site keeps their number whatever you set here; the settings decide what happens when they come back.

Setting Where What it does to the number
Attribution Model Attribution With First Click (the default), a returning visitor keeps their number until storage expires. With Last Click, a visitor who arrives again from outside your site is assigned a number again, for the source they came from this time.
Source Override Attribution (First Click only) A visitor who arrives from one of the sources you pick here is assigned a number again, for that source, even under First Click.
Max storage days Storage How long the visitor’s number is remembered (21 days by default). After that, they are assigned a number again, as a new visitor.
Storage expires N days after Storage Most recent visit (the default) counts the days from their last visit, so a regular visitor keeps their number. First page visit counts from their first visit, however often they come back.
Create cookie and Domain Storage Keep a copy of the visitor’s number in a cookie (on by default), so it carries across your subdomains when Domain is set to your domain (for example example.com).

Clicking Save & Publish also resets every visitor: after you publish, each returning visitor is treated as new and assigned a number again. This is by design, so publish changes when they are ready rather than one at a time.

DNI vs. source-based tracking

Source-based tracking

  • It assigns one fixed tracking number to a channel (for example, Google Ads).
  • Every visitor from that channel sees the same number, so attribution stops at the channel or campaign level.

Dynamic Number Insertion

  • It assigns numbers per session, so attribution can reach down to the keyword, ad variation, and landing page.
  • It’s the right choice when you need call data at the same granularity as your click data.

How many tracking numbers you need

Pool size depends on your peak concurrent visitors and average session length. Use the Nimbata number pool calculator to get a recommendation.

Detailed guide: Calculate your pool size

🎉 Ready to set it up? Continue with Set up DNI step by step.

Set up DNI step by step

Setting up DNI involves configuring your account first, then publishing the script to your website. Complete the steps below in order.

Configure your account

Before your script can go live, you must complete these five account configuration steps.

  1. Acquire your tracking number

    • Go to TrackingNumbers.
    • Click Add.
    • On the From step, choose the source you want to track, then click Next.
    • On the Tracking # step, pick the country and number type (the types depend on the country, for example Local or Toll-Free), and how many numbers you need.
    • Click Finish. If your project has no destination yet, there is a Destination step first: enter the number that should ring.

    Tracking Numbers

    Phone numbers that capture incoming calls and attribute them to a source.

    Search
    Group bySourceNone
    NameNumbersSourceCall Flow
    All online sources Pool· 2 numbers
    Tracking Num Pool(415) 555-0131US · LocalAll online sourcesMain line
    Tracking Num Pool(415) 555-0132US · LocalAll online sourcesMain line
    Google Ads· 1 number
    Emergency Repairs(415) 555-0142US · LocalGoogle AdsMain line
    Tracking Numbers: click Add (1) to get a tracking number.

    Tip

    Choose a number that matches your real business area code to maintain brand consistency.

    Detailed guide: Add your first numbers

  2. Name your tracking number

    • Give your number a descriptive name.
    • You can set this during setup or later by clicking the edit (pencil) icon next to any number in Tracking > Numbers.

  3. Add a destination number

    If you entered a destination when you added your number, Nimbata already added it as My Destination and assigned your number a Calls towards call flow: you can skip this step and the next one.

    • Go to Tracking > Destinations.
    • Click + Add.
    • Enter the phone number where calls should be forwarded.
    • This is where your business receives the call.

    Detailed guide: Add a destination

  4. Set up a call flow

    Detailed guide: Build a call flow

  5. Test your setup

    • Dial the tracking number from your mobile phone and confirm it rings at your destination.
    • Then check Activity > Calls to verify the test call appears in your logs.

Publish the DNI script

Once your account is configured (all five steps above are complete), you’re ready to go live.

  1. Open the script page

    Go to TrackingTracking Code in Nimbata.

  2. Configure your swap targets

    This is the most critical step. You need to tell Nimbata which phone number on your website to replace. Under Number Swapping, pick the Swap Type:

    • Phone Number (Match by exact number): enter the number under Swap Targets exactly as your website shows it, and the script finds it on your page and replaces it.
    • Span Tag (Match by CSS class, recommended for accuracy): Wrap your website number in a span tag: <span class="nimbata_number">123-456-7890</span> (with two or more swap groups, nimbata_number_1, nimbata_number_2 and so on)

    Tracking Code

    The script that swaps numbers on your website and attributes visitors to calls.

    Call TrackingForm Tracking
    Number SwappingAttributionStorageBrowser DataAdvanced

    Number Swapping

    Configure how tracking numbers are swapped on your website

    Swap Type
    Phone NumberMatch by exact numberSpan TagMatch by CSS class
    1Swap-Group 1
    Swap Targets
    (415) 555-01001
    All online sources2
    Add another swap group
    Number Swapping: with Phone Number selected, type your website's number into Swap Targets (1) and press Enter.

    You can also toggle additional options here, such as Single Page Site (SPA) support (on the Advanced tab) or how long visitors are remembered (Max storage days, on the Storage tab).

    Detailed guide: Use span tags

  3. Publish the script

    Click Save & Publish, then add the script to your site using one of these methods:

    Attribution scriptJavaScript
    1<script type="text/javascript" src="//cdn.dni.nimbata.com/hp-415-demo.min.js"></script>
    Paste this as the last item before the closing </body> tag on every page you want calls and forms tracked from.
    Script StatusDNI tracking configuration
    Last Updated2026-10-14 09:12:40Last activityNo activity recorded yet
    RemoveRe-publish
    Website URLhttps://harborpine.exampleVerify from my browser
    Once published, copy the script (1). Script Status shows when it was last updated and the last activity on your site.

Verify the installation

  • Live test: Visit your site; if you’re tracking all channels, the number should swap immediately.
  • Google Ads test: Visit www.yoursite.com/?gclid=test to force a swap for paid search numbers.
  • Built-in checker: Use Nimbata’s website URL checker, located just below the DNI script in TrackingTracking Code: enter your site under Website URL and click Verify from my browser.

🎉 Numbers swapping correctly? You’re live. Next, consider setting up swap groups if you want to track multiple numbers or channels independently.

Detailed guide: Set up swap groups
Troubleshooting: Numbers not swapping

One script per project

Nimbata generates one DNI script per project.

A single script handles any number of swap groups and tracking numbers within that project, so you rarely need more than one.

If you need separate scripts, for example to track two independent websites with their own pools and reports, create an additional project for each one.

Detailed guide: Create or duplicate a project