Airtel broadband has introduced new 1mbps and 2mbps unlimited plan without any FUP for Rs.699 & 1199 respectively.
You won’t find any of these plans on Airtel website as these plan are not available for everyone. Even now that you know the plan and it’s details, still one can’t opt for it by directly calling the customer care. 
These are retention plans only offered to customers who ask for disconnection by calling 121. Normal customer care executive can’t change to above plan. Customer who ask for disconnection are transferred to supervisor who are from retention department, the one who can change to these plans.
Plan 1199 with 2mbps unlimited is introduced to beat Bsnl broadband 1199 2mbps true unlimited plan though Bsnl plan is still cheaper with free unlimited calling. In airtel 1199 plan unlimited free calling can be availed opting for Rs.99 topup.
Plan 699 is costly and hopeless plan in all aspects. Should only be opted if one is satisfied with 1mbps which is useless in today’s world. Infact most cable/ethernet based isp offers several times better speed in same or even lesser amount. Even Tikona wireless 3mbps true unlimited can be considered on value terms keeping aside Tikona’s billing and network overloading problems.