Google Phone Tracking

I am trying to install Google Call Tracking into my website.

I have implemented some code into Google Tag Manager which is triggering on every page. I have also tried removing the code from Google Tag Manager and added it directly to the header.php file in my child theme, this also triggers on all pages.

The issue arises when adding the second part of the code.

I have to replace all phone numbers on the website with the following:

<script>
gtag(‘config’, ‘AW-819903212/j6PkCMfLn4EBEOz1-oYD’, {
‘phone_conversion_number’: ‘01454 315 779’
});
</script>

When I add this to a text block or a header it won’t save an allow me to return to editing the page.

Can you assist me with this please?