In order for the India to India domestic shipping to work you need to add in a PurposeOfShipment type to the request. This line is not standard in Magento's code for Fedex shipping. That line will be added into CustomsClearanceDetail header as a child under CommercialInvoice then a line under that is Purposewhich can have any value that PurposeOfShipment has.
Here is an example of the request I used that returned proper shipping estimates for India to India shipping.
'CustomsClearanceDetail' => array(
'CommercialInvoice' => array(
'Purpose' => "SOLD"
Also, Rates are not available for test credentials,use production for testing rates!