Originally Posted by rs_saravanan

I got A3232 model. This WCDMA network option came to me as surprise and checked with my colleague mobile who has same model. He did not have this option as I said before.
Later we found how to get WCDMA option.
Note: While changing the SIM card, this option got disappeared and we followed the following steps to bring it back;
This is the steps
1) Set the mobile to Airplane Mode
2) Switch off the mobile
3) Switch on the mobile now
Now go to the following menu
Settings >> Wireless Controls >> Mobile Networks >> Network Mode - Here you will find 3 options (Preferred Network mode)
1) WCDMA Only
2) GSM Only
3) GSM / WCDMA Auto
Please confirm whether you get above options

Also try this URL:
How to enable 3G in Google Nexus One Phone | Qcubicle