BSNL FUP is super erratic. I have 2 lines, both 4Mbps/175GB each. Some months I've gone well over 200-210 GB and then the FUP speed of 256 kbps hits and other months it hits exactly at 175 GB. Also, I've noticed it doesn't matter if you have the modem turned on during the speed reset. It'll automatically reduce the speeds during the session.