I can't speak directly for Safari, but a quick search looks like Firefox does not propagate the event up the DOM tree when a click event happens on a disabled element (see Event on a disabled input).
It looks like the information in your modal might be represented best in a different format. Try using Bootstrap's popovers or just placing the number to call near the disabled button.
If you still want to use a modal, you will have to follow the advice in the topic linked above in order to be cross-browser compatible. You can find the example here: JSFiddle
Here's a snippet of the HTML required to perform this "hack":
<span style="position:relative;">
<input type="text" disabled />
<div style="position:absolute; left:0; right:0; top:0; bottom:0; cursor: pointer;"></div>
</span>