For that only i hard resetted the phone to see if that can rectify the issue. But that too did not work. But i have earlier experienced speeds of more than 250 kBps using the same device.
Check this post of mine long time back.
http://www.techenclave.com/wireless-internet/workaround-use-bsnl-3g-cost-normal-161834-9.html#post1489414
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Is the modem available in stock with dvdstore ?? I guess not 
