Yes, they are capping, For me first eight days were a breeze and I crossed 300GB around of Downloads+Uploads ( Speed were like 1.4 MBps stable even during the day) but then after 280-300 GB speed became totally unstable sometimes it used to give 2 Mbps flat then it's back to fast 1MBps range. So I choose to switch off data for a day then restarted data, It gave 1MBps and above flat for 10-15 hours then again slow speed. I had another BSNL sim to check the speeds in which I did 1GB recharge and checked speed it was a breeze. So, I think there must be capping. I wouldn't blame BSNL 3G for that because I must be choking their network even I crossed 400GB for 498 Rs that's nearly 1GB per Rupee. Great going BSNL............