Just saw this news:

BSNL has revised the download speed after Fair Usage Policy Limit from 512 kbps to 1 Mbps for all existing and new unlimited FUP Broadband Plans from August 1. The download speed before FUP limit and data usage has also been increased in some of the existing broadband plans. For further details, visit www.bsnl.co.in or BSNL CSC.

Source : The Hindu

But can't find anything on BSNL website, and from the section it is published on news paper website, I suppose this is valid only for BSNL Kerala.