well.. facebook launched 0.facebook.com with the goal of providing it free to customers through partnerships with mobile service providers. if you try to access it through your desktop, it won't work for you because it detects your service provider against the list of partners and see that your ISP has not offered to provide it for free. if your ISP is not included, the service tells you to use mobile.facebook.com instead. 0.facebook.com is not a service from airtel wap portal. it is a service by facebook and it is supposed to be free no matter what. and if airtel is still being shown as an approved partner by facebook. and airtel users are allowed to access 0.facebook.com using their mobile phones. and airtel is charging for it... it is a clear case of cheating (facebook and the customer).