On the website link , the mobile phone number in the SAFARI browser is not shown at the bottom of the page, only "cellular:" and the number goes blank. In Chrome you see the text well, can it be the typography? 
<p>Celular: + 56 9 77973724</p>
<p>Email: [email protected] </p>Thanks
I see the same thing, I do not think it's the source but you can change it and do the test.
Searching in the source code I found the class that contains the style; it's called .extreme-left p and you can there add !important to the color so that they take precedence over other style rules that can be found on the page.
Updated:
Searching around the web a bit find this: x-apple-data-detectors that is used internally in some Apple applications in iOS and macOS to automatically insert links for certain types of information (such as phone numbers, dates and locations).
On the other hand, when you use numbers, try to do it like this: <p>Celular: +56.9.77973724</p> with periods or with hyphens.
a [x-apple-data-detectors]{
color: inherit !important;
}
-----------------------------------------------------
.extreme-left p {
color: black !important; // le agregas !important
margin-top: 3.5%;
display: block;
font-size: 14px;
}