XDA Developers member hubo2000 has posted another way to get the Samsung Omnia unlocked, in case you have had problems with previous attempts.
That being said, here are the steps that need to be taken to accomplish this seemingly simple task:
Go to the registry, HKCU\System\State\PHONE, and wrote down the first 6 digits of the value of the IMSI entry.
1. type *7465625*638*# to set
2. type the first 6 digits of the value of the IMSI entry here.
3. type your new NCK (12345678), then OK
3. type *#7465625# to check your lock (network lock still enabled)
4. type #7465625*638*# and type your NCK (12345678)
Let us know in the comments if this was of assistance in unlocking your Omnia.
See the original post here.