Its not 2 Mbps unlimited. OP has posted wrong info from wrong source. Its 2Mbps till 1GB and then 1Mbps unlimited which will be later migrated to 499 UL plan.
Check here - http://www.bsnl.in/opencms/bsnl/BSNL/services/broadband/entry_level_plan.html
Check here - http://www.bsnl.in/opencms/bsnl/BSNL/services/broadband/entry_level_plan.html