If your Nexus One device is constantly flip-flopping between 3G and EDGE data service, even though 3G is available, you can force it to use 3G only until a fix is released for the device.
1. Select Phone.
2. Dial the following:
3. The Testing screen will appear.
4. Select Phone information.
5. Scroll down to Set preferred network type:
6. Select the dropdown (the current value should read WCDMA preferred).
7. Select WCDMA only.
8. Go back to the Home screen and wait for your phone to reconnect to the network.