Call Tracking (Dynamic Number Insertion)
Call tracking is technology that connects an inbound phone call back to the online journey that led to it — the website visit, the pages viewed and the marketing source that drove the customer to pick up the phone.
At ACXPA we've historically called this Web Voice Synchronisation (WVS); the wider industry calls it call tracking.
The engine behind it is Dynamic Number Insertion (DNI). A small piece of code shows each website visitor a unique phone number, so when they call, the system can match that call to their exact session — source, keywords, landing page and all.
For a contact centre, that turns a "cold" inbound call into a warm one: the agent can see how the customer arrived and what they were looking at, the business can route or prioritise the call, and marketing can finally attribute phone conversions to the campaigns that earned them.
This guide explains what call tracking is, how DNI works, what data reaches the agent, the benefits, and the privacy points to get right.
What it is
Technology that ties an inbound phone call to the web visit and marketing source behind it, using a unique tracking number shown to each visitor.
Why it matters
It gives agents context for a more personalised call, lets the business route high-value calls, and connects phone conversions to marketing spend.
What this guide covers
What call tracking is, how Dynamic Number Insertion works, what the agent sees, the benefits, and the privacy and accuracy points to watch.
What is Call Tracking?
In plain English
Most businesses can see exactly how their website performs — which ad sent a visitor, what they searched, which pages they read.
The moment that visitor picks up the phone, all of that usually disappears. Call tracking is what keeps the thread connected: it links the phone call to the web session that produced it, so the journey doesn't go dark the instant it leaves the screen.
It does this by giving each visitor a unique phone number to call. Because the number is tied to that specific visit, the call can be matched back to everything the business already knew about the session — the source, the keywords, the pages, the time on site.
That single link unlocks two things at once: smarter handling of the call in the contact centre, and accurate attribution of the call back to marketing.
What it is
A way to connect inbound phone calls to the online journey behind them, so agents get context and marketing gets attribution. ACXPA's term for it is Web Voice Synchronisation.
What it isn't
It is not call recording or call monitoring, and it doesn't change the customer's experience on the website — the unique number is the only visible difference.
What is Dynamic Number Insertion (DNI)?
Dynamic Number Insertion (DNI) is the mechanism that makes call tracking work. A small piece of JavaScript on the website swaps the phone number shown on the page for a unique tracking number, chosen for that individual visitor and their session.
Two people on the same page at the same time will see two different numbers — each one quietly tied to how that person arrived.
The key distinction
Call tracking is the overall capability; DNI is the specific technique that powers the most useful version of it.
You can do basic call tracking with static numbers — a different fixed number per channel, such as one for a print ad and another for a billboard. DNI takes it to the visitor level, which is what allows session-by-session detail like the exact keyword or landing page to follow the call through.
How Call Tracking Works
From the customer's side, nothing looks unusual. Behind the scenes, a few steps connect their visit to their call.
Visitor arrives
Someone lands on the website. The tracking code captures how they got there — the ad, search keyword, referral or campaign — and their behaviour on the site.
A unique number is shown
DNI displays a phone number reserved for that visitor's session, so any call they make can be traced straight back to it.
The customer calls
When they dial that number, the call routes through the tracking platform and on to the contact centre as normal — no delay the customer would notice.
The call is matched
The platform links the call to the visitor's session and passes that context to the agent's screen and to routing — and records the conversion for marketing.
What the Agent Sees
The value of call tracking lands the moment the conversation moves from the web to the contact centre. Instead of starting cold, the agent can be handed the context of the visit that prompted the call.
🧭 The journey
How long the customer spent on the site, the pages they visited, where they landed and the page they were on when they called — a clear picture of what they were trying to do.
🔎 The source
The keyword, campaign, ad or referral that brought them in — useful both for the conversation and for marketing attribution.
⭐ The likely value
Smarter setups can predict the value of a call from the path the customer took, so high-value calls can be prioritised or routed to the right agent.
Why that context matters
An agent who can see what the customer was looking at can help faster, personalise the conversation and resolve the enquiry in fewer steps — which lifts conversion in a sales setting and reduces customer effort everywhere else.
It also feeds smarter routing: a call from a high-intent page can jump the queue or go straight to a specialist.
Why It Matters
Call tracking earns its place by serving three groups at once — the contact centre, the customer and the wider business.
🎧 For the contact centre
Agents handle calls with context, not guesswork — faster resolutions, better upsell, and the ability to route or prioritise based on where the call came from.
👤 For the customer
A more personalised conversation that takes less effort. They don't have to re-explain what they were doing — the agent already has the picture.
📈 For the business
Phone conversions are finally attributed to the campaigns that drove them, so marketing spend can be measured and aimed at what actually generates calls.
The attribution gap it closes
For any business that markets online but sells or services over the phone, the phone call has long been the blind spot in the funnel.
Call tracking closes that gap — connecting marketing technology to the contact centre so the whole journey, click to call, can be seen and improved.
Privacy & What to Watch
Call tracking is powerful precisely because it joins web behaviour to a phone call and a person — which is exactly why it has to be handled with care.
Privacy & consent
You're tracking visitor behaviour and linking it to an identifiable person. Be transparent about it, handle the data under your privacy obligations, and make sure your website's consent and privacy notices actually cover it.
Attribution accuracy
Results are only as good as the setup: too small a pool of tracking numbers, or visitors who share a number, can blur the link between a call and its true source.
The Australian privacy angle
In Australia, joining a person's web activity to their phone call and storing it engages the Privacy Act and the Australian Privacy Principles where personal information is involved.
Be clear in your privacy policy and collection notice about what you capture and why, collect only what you need, and check current obligations with a qualified adviser — privacy rules change. This isn't legal advice.
💡 Finding a provider
Call tracking and DNI are delivered by specialist platforms that integrate with your website, telephony and analytics.
To compare options, browse Call Tracking suppliers in the ACXPA Supplier Directory.
Frequently Asked Questions About Call Tracking
What is call tracking?
Call tracking is technology that links an inbound phone call back to the website visit and marketing source that produced it. Each visitor is shown a unique phone number, so when they call, the platform can match the call to their session — the source, keywords and pages — and pass that context to the agent while recording the conversion for marketing.
What is Dynamic Number Insertion (DNI)?
Dynamic Number Insertion is the mechanism behind visitor-level call tracking. A piece of JavaScript on the website swaps the displayed phone number for a unique tracking number tied to each visitor's session, so the call can be traced back to exactly how that person arrived — down to the keyword and landing page.
What's the difference between call tracking and DNI?
Call tracking is the overall capability; DNI is the specific technique that powers its most detailed form. You can do basic call tracking with static numbers — a fixed number per channel, like one for a print ad and another for a billboard. DNI works at the individual-visitor level, which is what lets session detail like the exact keyword follow the call through.
What is Web Voice Synchronisation?
Web Voice Synchronisation (WVS) is ACXPA's term for call tracking — specifically the version that passes a customer's web journey through to the contact centre agent when they call. It's the same technology the wider industry calls call tracking, built on Dynamic Number Insertion.
What data can call tracking pass to a call centre agent?
Typically the time spent on the site, the pages viewed, the landing page and current page, the search keyword, and the referral, ad or campaign source. Smarter setups can also estimate the likely value of the call from the path taken, so it can be prioritised or routed to the right agent.
Does call tracking only work for online channels?
No. Visitor-level detail comes from DNI on a website, but you can also use static tracking numbers for offline channels — a unique number on a print ad, billboard, vehicle or letter — to measure which offline source drives calls. You lose the session-level detail, but you still attribute the call to a channel.
Is call tracking a privacy concern?
It can be, because it links web behaviour to an identifiable person's phone call. Used responsibly it's fine, but you need to be transparent about what you collect, handle it under your privacy obligations, and ensure your consent and privacy notices cover it. In Australia this engages the Privacy Act where personal information is involved — confirm current obligations with a qualified adviser.
Where to Next
Summary: Call Tracking
Call tracking is technology that links an inbound phone call back to the website visit and marketing source that produced it — known at ACXPA as Web Voice Synchronisation, and powered by Dynamic Number Insertion (DNI), which shows each visitor a unique number so their call can be matched to their session.
It keeps the customer journey connected at the point it usually goes dark: the moment a web visitor picks up the phone.
For the contact centre, that means agents handle calls with context and can route or prioritise by source; for the customer, a more personalised, lower-effort conversation; and for the business, phone conversions that are finally attributed to the marketing that drove them.
The trade-off is responsibility: because it joins web behaviour to an identifiable person, it has to be set up with privacy, consent and accuracy in mind — in Australia, with the Privacy Act in view. To compare platforms, see Call Tracking suppliers in the ACXPA Supplier Directory.
