how to detect that downloading has stopped

My Reliance CDMA net has some clever mechanism,
that it often doesn't disconnect even when downloading stops from net.

It remains connected and keeps on uploading something to somewhere, which wastes my bandwidth as it still counts the uploaded data as having consumed my bandwidth.

waste of bandwidth is one problem, another problem is I don't come to know that download is not working from net, so when I need net and try to download something or load some page in browser, then I come to know that net has stopped.

Also, though it keeps on sending some data to somewhere, if I try to send something, or send a a mail, it doesn't send.

Any clue how to tame my USB dongle from immediately disconnecting when it is not able to download anything.

or, I need some software that automatically downloads small quantity of data (even a byte or a bit) at fixed time interval (every minute), and gives a signal if it is not able to download the data. Any tips.

Thanks.
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RAwat