Check it is working

Two minutes to be sure. Do this once after installing, and again after any theme or template change — a redeploy that drops the tag looks exactly like nothing being wrong.

The quickest check

1. Open your site in a private or incognito window. Do not skip this: if you have visited before, you already hold a visitor cookie and will see the number you were given last time, which tells you nothing about whether the tag is live now.
2. Look at your phone number. It should differ from the one in your template — same formatting, different digits.
3. Ring it from your mobile. The call should reach your normal line within a second or two.
4. Open your call log. The call appears within a few seconds, with a channel attached.

Testing that attribution is right

To prove a channel is being distinguished rather than everything landing in one bucket, visit with a click identifier attached and confirm you get a different number:

https://yoursite.co.uk/?gclid=test123

In a fresh private window that should show a different number from a plain visit. Ring it, and the call should appear attributed to paid search rather than direct.

A fabricated gclid will not resolve to a real keyword — Google has no record of it, so the keyword shows as not found. That is correct behaviour and not a fault.

When the number is not swapping

In rough order of how often each is the cause:

1. Your domain is not in your tracking domains

The tag refuses to run on a domain it does not recognise — that is what stops someone else using your key. If you have just added domains, note that example.com automatically covers www.example.com, but a completely separate domain needs listing on its own. Check Tracking, which also lists any host we have seen using your key that is not in your list.

2. The number is an image

The tag can only change text it can read. A number inside a logo, a banner, or a <canvas> cannot be swapped. Neither can one inside a third-party chat widget's iframe. If your header number is part of an image, that is worth fixing for tracking and for screen readers.

3. The tag is not actually on the page

View source and search for data-ct-key. If it is missing, the template edit did not save or a caching layer is still serving the old page. Clear your CDN or page cache.

4. You are looking at a cached page

Static hosts and CDNs will happily serve a version of your page from before the tag was added. A hard refresh is not always enough — purge the cache.

5. The number on the page is written unusually

We match on the last nine digits, which covers spacing, brackets and country codes. A number split across HTML elements — the area code in one <span> and the rest in another — cannot be matched, because there is no single piece of text to replace.

When the caller hears an apology instead of your phone

"Thank you for calling. We are unable to connect you at the moment." means the number reached us correctly but we have nowhere to send it — no forwarding number is set for that website. Set it on Numbers; calls arriving afterwards connect normally.

Worth checking specifically, because everything else looks healthy in this state: the number rings, the call appears in your log with a channel attached, and the tag is clearly working. The only symptom is that nobody ever reaches you.

When a call arrives but has no channel

The call reached you and was logged, but shows as unattributed. Usually one of:

• They rang your real number, not the tracked one. From an old bookmark, a directory listing, a Google Business Profile, or a printed leaflet. Nothing to fix — those calls genuinely did not come from your website.
• They saw the fallback number. Your pool was exhausted at that moment. Marked coarse in the call log; add numbers if it happens often.
• They arrived before the tag loaded. Rare, and more likely if the tag is installed through Tag Manager rather than directly in the head.

A note on testing repeatedly

Your own test calls appear in your call log and count towards your answered-call allowance like any other. A handful is nothing. If you are testing extensively — an agency checking forty clients, say — tell us and we will not count them.

Ringing the same number many times in quick succession may also raise its spam score, which would exclude those calls from billing. That is the system working, but it can make your own test calls look odd in reporting.