Use the preprocess function, like:
function YOUR_THEME_preprocess_field(&$variables) {
$element = $variables['element'];
if (isset($element['#field_name'])) {
if($element['#field_name'] == 'field_business_phone') {
foreach ($variables['items'] as $k => $value) {
$variables['items'][$k]['#markup'] = '<span class="glyphicon glyphicon-earphone list-icon"></span>' . $variables['items'][$k]['#markup'];
}
}
}
}
Or overwrite the field templates, in a file named field--field-business-phone.tpl.php, containing something like:
<?php
<div class="<?php print $classes; ?>"<?php print $attributes; ?>>
<?php if (!$label_hidden): ?>
<div class="field-label"<?php print $title_attributes; ?>><?php print $label ?>: </div>
<?php endif; ?>
<div class="field__items"<?php print $content_attributes; ?>>
<?php foreach ($items as $delta => $item): ?>
<div class="field__item <?php print $delta % 2 ? 'odd' : 'even'; ?>"<?php print $item_attributes[$delta]; ?>><span class="glyphicon glyphicon-earphone list-icon"></span> <?php print render($item); ?></div>
<?php endforeach; ?>
</div>
</div>