How to Disable Data Connection on Android Phone

I have an embarrasing experience using an Android phone for the first time. I set up the Internet connection with 3G/GPRS and the phone kept connecting and transmitting/receiving data until I ran out deposit on my prepaid GSM plan. I browsed through the phone setting there was nothing to set the data connection off.

There is an undocumented instruction (at least, on my phone manual) to turn data connection off and back on, on demand. you can do this:

1. First, open phone dialer,
2. Press *#*#4636#*#* to bring up Testing screen,
3. Tap on Phone Information on the menu,
4. Press menu button on the phone,
5. Choose More,
6. Tap on Disable data connection.

The currently active data connection will disconnect immediately.