If your browser is bundled with the Skype plugin, it will automatically wrap the phone number with Skype format. This can be avoided by adding a invisible text anywhere in the phone number.
<!-- Orginal --> <div>852 12345678</div> <!-- Prevent the Skype plugin to work --> <div>852 1234<span style="display:none;">_</span>5678</div>
Done =)
Reference: 1066internet – Prevent Skype from converting a phone number