Cheetah, You can recharge for 4200/- and get the plan, currently Data Roaming is free, But confirm from BSNL office before you spend such huge amount.Remember roaming plan can be modified at later date, as lots of private operators are coming up, nobody knows what they'll modify at a later date.to be on safer side, use the SIM from region you happen to live most of the time, this way you'll minimize the chances of getting charged for roaming.