Custom Contact Us page for SharePoint online Public facing site

Hi,

     We are working on branding our SharePoint online site. Below is url of our SharePoint online site: https://sharepointonlineempower-public.sharepoint.com/

      We want to use our own custom Contact us page and want to insert entries in the Contact List. We don't want to use below Contact Us Form provided by Office 365 forum

http://office.microsoft.com/en-in/office365-sharepoint-online-enterprise-help/add-a-contact-us-form-app-to-your-website-HA102845395.aspx

We need to use our own form. We have created our own Custom Form and on Submit button click we are using REST API/CSOM callout which is working fine whenever we are logged into our SharePoint online but it is not working for public facing web site for anonymous users.

What is work around to make REST API calls for public facing web site as it is not working for Public facing site or how can we have our custom contact us page for Public facing site.

Thanks

Paras Sanghani

www.sharepointempower.com

www.parassanghani.blogspot.in