How to display a non-cached area in the bitrix site header?

Question

1C-Bitrix

Hello!
I'm trying to dynamically change the phone number in the site header (header.php) depending on the traffic source.
The site is based on CMS 1C-Bitrix, autocaching is working and the "composite site" mode is enabled.
The algorithm is as follows:
When a visitor goes to the site, information from the utm tag is written to the cookie.
Next, in the place where you need to display the phone number, the $_COOKIE['utm_source'] value is checked for a match with "YandexMarket" and "YandexDirect", and if it matches, a special phone number is displayed.
The problem is that in order to display the desired number, you need to refresh the page several times ...
I deleted the cache of the site and the browser.
I tried to use the solution from the marketplace "TS Non-cached area", everything is the same.
The page works with web forms that also use the $_COOKIE['utm_source'] value, when filling out these forms everything works as it should.
Thank you in advance!

Answer 1

The reason is most likely in the composite, you need to bring the output and the code to get the number into the dynamic area
, here are examples, well, keep in mind whether this is a component template or a site template
https://dev.1c-bitrix.ru/learning/course/index.php. ..