More about Samsung X105...

From http://cellphoneforums.net/t118967.html:
Unlocking your Samsung All Models
Tested on x426, x427, e105, e715



EX: you are using phone Samsung e105 which is locked by T-Mobile, and now you
want to use it with ATT. Do these step correctly and you get your phone unlocked.

* You have to have ATT SIM card with you, and now suppose that T-Mobile SIM card
is in your phone. Here we go:

1. Change your phone's password back to 00000000 (8 number zero)
2. Power off your phone.
3. Take battery out --> take your T-Mobile SIM card out of the phone
4. Put ATT card in side the phone --> put battery back --> power phone on.
5. WRONG CARD message would appear on screen (in some case if the phone ask SIM
  unlock code , just put any number and it will show that message)
6. Enter *#9998*3323# and you see option exit ---> press right softkey to use
  function EXIT
7. After that one menu will show up, use arrow key go to number 6(or 7) Malloc
  Fail and use right softkey to choose this one.
8. Your phone will auto restart and now ATT network show on screen
*  Until now your phone temporary unlocked ATT SIM CARD, to unlock your phone
  forever, please continue:
9. On screen, press *0141# and hit call button then screen appear "Persernalized"
10. Turn off phone --> take ATT SIM out --> put T-Mobile SIM in --> Power on
11. Screen ask " SIM unlock code"
12. Please enter 8 number zero : 00000000 ---> OK
CONGRATULATION,
Your phone now is unlocked.