Ranjit:lg cu720 model unlock how to use - AT&T LG CU720 Cell Phone - Silver

SOURCE: unlock code for LG cell model cu720

On the AT&T Network, to unlock the LG Shine or CU720, it’s pretty simple:

• Put a AT&T or Cingular SIM in the phone; it does not have to be an active SIM
• Enter *#865625# then the 16 digit unlock code*
• Device should say: Network Lock Deactivated
• Phone may automatically reboot

*The 16 digit code can be obtained by calling AT&T Technical Support and given the representative the IMEI number. In exchange they will give you the Subsidy Unlock Code.
To obtain the IMEI number, type *#06# on your device. This is a 17 digit number and it is not the same as the unlock code, this is the IMEI number to give to AT&T Technical Support in exchange for the 16 digit Subsidy Unlock Code.

to get the (16 digits code) call att and tell them you are traveling overseas, it may take two calls.
,but they should give it to you the (16 digits code)
OR
Insert non ATT SIM
Power up
Showing 'Invalid Smart Chip'
Enter *#865625#
This will take you to a screen saying you are about to unlock your phone. Do you want to proceed.
Select yes (left button)
Enter your 16digits code.
Hit OK
Enter your code again
Hit OK.

Now the phone is unlocked

It requires 2 inputs of the unlock code.
If this helps solve your problem please give a fixya rating, all of them are really appreciated, sorry I cant personally tell you the code number, but ATT or your Service provider should, if all else fails, here's an online service.
http://www.mobileunlocked.com/LG/CU720_Shine