Call tracking

Some customers get in touch by phone. Call tracking is how a business works out which advert, listing or web page led someone to call.

What it does

Call tracking software records information about incoming phone calls. For phone calls, it does the job that conversion tracking does for sales made online.

A number for each advert

One form gives each advert its own phone number. A leaflet, a newspaper advert and a banner online each show a different number. A call to that number is counted against that advert.

A business choosing numbers can check what callers will pay. GOV.UK sets out the main kinds. Numbers starting 01 and 02 belong to parts of the UK, and 03 numbers cover the whole country. GOV.UK puts 03 numbers in the same cost band as 01 and 02 numbers, from landlines and from mobiles. Calls to 0800 and 0808 numbers are free.

Numbers that change on a website

On a website, call tracking works through a small piece of code that the provider supplies for each page. When the page loads, the code swaps the phone number shown for a tracking number.

One approach gives each source of visitors its own number. Visitors from a search advert see one number, and visitors who found the site in ordinary search results see another. That shows which source brought the call, though not which visit.

A second approach keeps a pool of numbers and lends one to each visit for a while. If the visitor rings that number, the call can be linked to the pages they looked at.

A third method skips the number altogether. The visitor leaves their own number on the website and the system connects the call. A cookie records which advert they came from.

The rules for the website part

The Information Commission (which took over from the ICO on 30 September 2026) has guidance on technologies that store or read information on a visitor's device. It says the rules apply to any such technology, including tracking pixels, scripts and tags as well as cookies.

A business must get the visitor's consent first, unless one of five exceptions applies. One covers storage or access whose only purpose is collecting statistics about how the service is used, so it can be improved. A business relying on that exception must offer visitors a simple, free means of objecting.

It also says the exceptions are narrow and will not apply in every case. A business deciding whether one applies must consider that exception's specific requirements.

Callers' details

A tracking system can hold callers' phone numbers alongside the pages they visited. The Information Commission's guide explains that personal information is information relating to a person who can be identified, and that a number or a cookie identifier can be enough to identify someone.

Some systems also record calls. Ofcom says several laws cover recording phone calls, and that anyone who needs help in this area should seek legal advice.

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