<a href="tel://+77779444471" class="callback-bt">
   <div class="text-call">
      <span>Позвоните<br>нам!</span>
   </div>
</a>

<style>
    /*кнопка звонка*/

.callback-bt {
    background: #38a3fd;
    border-radius: 50%;
    box-shadow: 0 8px 10px rgba(56, 163, 253, 0.3);
    cursor: pointer;
    border: 2px solid transparent;
    display: block;
    height: 75px;
    width: 75px;
    text-align: center;
    position: fixed;
    right: 8%;
    bottom: 25%;
    z-index: 999;
    transition: .3s ease-in-out;
    -webkit-animation: hoverWave linear 1s infinite;
    animation: hoverWave linear 1s infinite;
}

.callback-bt:hover {
    background: #fff;
    border: 2px solid #38a3fd;
}

.callback-bt .text-call {
    height: 75px;
    width: 75px;
    border-radius: 50%;
    position: relative;
}

.callback-bt .text-call:after {
    content: "\f095";
    display: block;
    font-family: fontawesome;
    color: #fff;
    font-size: 38px;
    line-height: 75px;
    height: 75px;
    width: 75px;
    opacity: 1;
    transition: .3s ease-in-out;
    animation: 1200ms ease 0s normal none 1 running shake;
    animation-iteration-count: infinite;
}

.callback-bt .text-call:hover:after {
    opacity: 0;
}

.callback-bt .text-call span {
    color: #38a3fd;
    display: block;
    left: 50%;
    top: 56%;
    position: absolute;
    transform: translate(-50%, -50%);
    opacity: 0;
    font-size: 10px;
    line-height: 12px;
    font-weight: 600;
    text-transform: uppercase;
    transition: .3s ease-in-out;
    font-family: 'montserrat', Arial, Helvetica, sans-serif;
}

.callback-bt .text-call:hover span {
    opacity: 1;
}

@keyframes hoverWave {
    0% {
        box-shadow: 0 8px 10px rgba(56, 163, 253, 0.3), 0 0 0 0 rgba(56, 163, 253, 0.2), 0 0 0 0 rgba(56, 163, 253, 0.2)
    }

    40% {
        box-shadow: 0 8px 10px rgba(56, 163, 253, 0.3), 0 0 0 15px rgba(56, 163, 253, 0.2), 0 0 0 0 rgba(56, 163, 253, 0.2)
    }

    80% {
        box-shadow: 0 8px 10px rgba(56, 163, 253, 0.3), 0 0 0 30px rgba(56, 163, 253, 0), 0 0 0 26.7px rgba(56, 163, 253, 0.067)
    }

    100% {
        box-shadow: 0 8px 10px rgba(56, 163, 253, 0.3), 0 0 0 30px rgba(56, 163, 253, 0), 0 0 0 40px rgba(56, 163, 253, 0.0)
    }
}

/* animations icon */

@keyframes shake {
    0% {
        transform: rotateZ(0deg);
        -ms-transform: rotateZ(0deg);
        -webkit-transform: rotateZ(0deg);
    }

    10% {
        transform: rotateZ(-30deg);
        -ms-transform: rotateZ(-30deg);
        -webkit-transform: rotateZ(-30deg);
    }

    20% {
        transform: rotateZ(15deg);
        -ms-transform: rotateZ(15deg);
        -webkit-transform: rotateZ(15deg);
    }

    30% {
        transform: rotateZ(-10deg);
        -ms-transform: rotateZ(-10deg);
        -webkit-transform: rotateZ(-10deg);
    }

    40% {
        transform: rotateZ(7.5deg);
        -ms-transform: rotateZ(7.5deg);
        -webkit-transform: rotateZ(7.5deg);
    }

    50% {
        transform: rotateZ(-6deg);
        -ms-transform: rotateZ(-6deg);
        -webkit-transform: rotateZ(-6deg);
    }

    60% {
        transform: rotateZ(5deg);
        -ms-transform: rotateZ(5deg);
        -webkit-transform: rotateZ(5deg);
    }

    70% {
        transform: rotateZ(-4.28571deg);
        -ms-transform: rotateZ(-4.28571deg);
        -webkit-transform: rotateZ(-4.28571deg);
    }

    80% {
        transform: rotateZ(3.75deg);
        -ms-transform: rotateZ(3.75deg);
        -webkit-transform: rotateZ(3.75deg);
    }

    90% {
        transform: rotateZ(-3.33333deg);
        -ms-transform: rotateZ(-3.33333deg);
        -webkit-transform: rotateZ(-3.33333deg);
    }

    100% {
        transform: rotateZ(0deg);
        -ms-transform: rotateZ(0deg);
        -webkit-transform: rotateZ(0deg);
    }
}
/* конец кнопки звонка */
</style>
<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/4.6.3/css/font-awesome.min.css" />

<a href="tel://+77779444471" class="callback-bt">
   <div class="text-call">
      <span>Позвоните<br>нам!</span>
   </div>
</a>