How to force the phone to connect to the internet?
Finally found a way to connect to internet on my Xperia Mini Pro android mobile.

Go to 
     Settings ==> Wireless &amp; network settings ==> Mobile networks ==> Network Mode
Its going to open another window with title as Preferred network mode.

Now try to Select WCDMA only option. Wait for 10 sec. We can see the network is getting reset and try to find the 3G signal. 
Now open the same pop up again and select GSM(Edge or 2G) connection. Now again networking related stuff gets reset again.

This is how I force my mobile to connect to internet.