1.First activate any Aircel 3G packs,higher than Rs 8 pack [e.g.:Rs 17,39 or higher]. Use all the 3G Data.
2.After the exhaustion of your 3G data you get 128kbps speed.Browse for atleast 10 minutes.
3.Then again activate the Rs 8 pack.It will give 50 MB of 3G data.When you have finished you 50 MB of 3G data,again the speed will be 128kbps.
4.From next day after 12 P.M. your speed will be again 3G.But only for a few moments may be 30 to 40 MB.Then your net will be disconnected and when you will reconnect,it will give 128kbps speed.
5.Now the real trick begins.When you starts getting 128kbps speed ,you have to do one thing.
6.Firstly, you have to deactivate your 3G services by sending "STOP 3G" to 121.
7.and then Secondly, after the confirmation message ,you have to again activate your 3G service not by sending message.Instead you have to dial *122*3344#
8.you will get 50,100,200,250 depending upon your pack.After that it will disconnect.but the real trick here.
9.again send STOP 3G to 121 but remember that you must be in utms (3g) mode means the signal should be in 3g.
10.after sending you will get the 2-3 conformation message. but you will see that the 3g signal is sill present there .
11.Done now connect you will get 500-600kbps speed just doing this till the network does not ends.
Checked this in micromax modem and it is working for me so just try and leave comment.