<link href="//maxcdn.bootstrapcdn.com/bootstrap/3.3.0/css/bootstrap.min.css" rel="stylesheet" id="bootstrap-css">
<script src="//maxcdn.bootstrapcdn.com/bootstrap/3.3.0/js/bootstrap.min.js"></script>
<script src="//code.jquery.com/jquery-1.11.1.min.js"></script>
<!------ Include the above in your HEAD tag ---------->
<form class="form-horizontal">
<fieldset>
<!-- Form Name -->
<legend>Ligaremos para você!</legend>
<!-- Text input-->
<div class="form-group">
<label class="col-md-4 control-label" for="fone">Digite seu telefone com o DDD:</label>
<div class="col-md-4">
<input id="fone" name="fone" type="text" placeholder="" class="form-control input-md" required="">
<button id="ligar" name="ligar" class="btn btn-success">Ligar-me!</button>
<span class="help-block">Insira seu telefone com o DDD da sua localidade. Ex.: 3521069000</span>
</div>
</div>
</fieldset>
</form>
