Finally I decided to shift my mobile Internet connectivity from GPRS to HSDPA by getting a Mobitel 3G broadband connection.
Read about it here
Huawai E220 is known to work out of the box on Linux after 2.6.20. However, some of the most recent kernels seems to have a conflict with the USB mass storage driver. It means, the disk drive in the modem with Windows drivers get detected, but not the modem. I am presently running Linux 22.214.171.124, which also exhibits this behavior.