Do you have free minutes, like first 5 minutes free, to call to different numbers and do you pass them always? Get this app from the market, you can register your numbers in the app and configure the calling time and it will disconnect before the minutes you registered. The best thing is it will call back automatically. So you can keep on calling without passing more.
It will also vibrate 15 seconds before it disconnects. It works great.
Send from my GT-I9000 Doc's ROM v9.9.5 Kitchen JS8 using XDA app powered by tegrak's kernel.