pushlabs

This plugin is an easy and simple way to add a call button to your website for your mobile users. This plugin aims to increase conversions and drive sales by enticing customers to click the button and immediately get in contact with you.
The only thing required to activate the plugin is to enter your phone number and you are good to go!
Additionally, there are a ton of optional features to use to customize the button:
<ul>
<li>Mobile Breakpoint: Set the pixel breakpoint when you would like your button/banner to appear.</li>
<li>Styles: Call Button comes with two different styles: the button, and the banner.</li>
<li>Button Position: Position your button to the left, middle, or right!</li>
<li>Button Size: Choose between three button sizes: small, medium, and large.</li>
<li>Button Background Color: Customize the background color of your button.</li>
<li>Button Icon Color: Change the icon color to your choosing.</li>
<li>Button Shadow: enable/disable the shadow of the button.</li>
<li>Button Border: enable/disable the border of the button.</li>
<li>Button Border Color: Customize the color of the border.</li>
<li>Banner Background Color: Customize the background color of your banner.</li>
<li>Banner Border Color: Add a border to your banner if you would like!</li>
<li>Banner Text: Add engaging text to your banner to provoke action!</li>
<li>Banner Font size: change the font size</li>
<li>Banner Text color: change the text color</li>
<li>Metabox with customizable settings for each page post.</li>
</ul>
As mentioned, Call Button also includes a metabox on each page/post where you can customize the phone number, style, or disable the button/banner for that page/post only!

Call Button

A modern, easy to use call button that shoots to increase conversions and drive sales!

ssik

The Easy Floating Call Now Button plugin allows you to add a highly customizable “Call Us” button to your WordPress site. Features include:
<ul>
<li>Customizable colors for button and text</li>
<li>Mobile and desktop visibility settings</li>
<li>Lightweight and efficient design</li>
<li>Fully responsive</li>
</ul>

Easy Floating Call Now Button

Adds a customizable floating call button to your website.

Call Button vs Easy Floating Call Now Button