Help me to recharge BSNL EVDO prepaid ??


I Bought a modem online from a guy from Rajasthan(jaipur).He used modem for 2months with 750UL plan.He sold it with sim card too.I want to recharge with 750UL plan .. to use in Karnataka. How should i do ? I tried to recharge with 830rs(as he used to inrajasthan) in Karnataka but it said request is invalid... i tried 825rs 825rs nothing worked !! Help me to recharge ..

P.s : The modem has a message in inbox which says "You have consumed 56.45MB.Your balance: 160Rs. Expiry date: 17-10-2011 reloadable up to 01-11-2011.Your Unlimited internet pkg.EXP:19-09-2011."