You can Unlock the samsung Comback SGH-T559 Model Phone using the Unlock code,You can get the Unlock code and instructions at here
Mobile-unlocker.com and Unlock it,then use with any GSM Network sim card....
Unlocking instructions:
Warning : Do not enter any wrong unlock
codes on your Samsung SGH-T559 Comeback mobile phones. If you enter over
a certain amount of wrong unlock codes on your Samsung SGH-T559
Comeback mobile phone, your phone may get hard locked and sometimes
become unusable.
Method 1:
1 - Switch ON your Samsung SGH-T559 Comeback with a
NOT ACCEPTED SIM Card.
2 - Samsung SGH-T559 Comeback will ask for "Password".
3 - Enter the Unlock Code.
OR (if the Samsung SGH-T559 Comeback shows "Insert Correct SIM Card")
Method 2:
1 - Switch ON your Samsung SGH-T559 Comeback with a
NOT ACCEPTED SIM Card.
2 - Don't bother about what's being displayed on your Samsung SGH-T559 Comeback.
3 - Compose :
#0111*CODE#.
NOT ACCEPTED: We mean, to use a sim card from a network other than the network your Samsung SGH-T559 Comeback is locked to.
CODE: Its the unique Unlock Code for your Samsung SGH-T559 Comeback.
If method 2 does not work, you can try method 2 again but this time without any SIM card on your Samsung SGH-T559 Comeback.