Looking at the documentation of the external service, there is an important note about placing the class on the <a> element directly if you want it to be clickable.
So, in your menu, you can try updating the <span> element to <a>:
<a class=“rulertel”>CALL NOW</a>
This will likely create multiple <a> elements in that menu item and might not be the cleanest implementation, but it should not show up on the front end or interfere with making the number dynamic, so it might work for the use case.