I recently purchased a locked SGH-J700(V) and, after quite a bit of looking and researching, found the way to completely and freely unlock it without zeroizing the IMEI using purely software and no need for cables.
DO NOT UNDER ANY CIRCUMSTANCES ENTER #*7337# if you do, it will zeroize your IMEI and brick your phone.
Power on your phone, enter *#7465625# - make a note of what codes are active
Power off phone
Partially insert SIM card and slip the battery in under it. You will need to be able to slide the SIM in the rest of the way without removing the battery.
Power on phone, it should come up and say "insert SIM" - at this point you do NOT insert the SIM yet
Enter *2767*3855# - this will wipe the settings on the phone and cause it to reboot.
Before it reboots, insert your SIM card without removing the battery
After a reboot, the phone should be working with that SIM, whether or not it was able to work with it in the past. Your phone is NOT yet unlocked.
For each of the locks that were active in step one reset the lock codes:
Network Lock: *7465625*638*00000000*00000000#
CP Lock: *7465625*27*00000000*00000000#
SP Lock: *7465625*77*00000000*00000000#
Subset Lock: *7465625*782*00000000*00000000#
Then, to disable the locks:
Subset Lock: #7465625*782*00000000#
SP Lock: #7465625*77*00000000#
CP Lock: #7465625*27*00000000#
Network Lock: #7465625*638*00000000#
Once this is completed, you can verify that all locks are inactive by looking in *#7465625# again. SIM Lock and Phone Lock are set in the security menu and can be disabled or enabled by the user at their convenience. They are not important for this procedure.
Note: I have been told that this did not work properly with original Vodafone SIM inserted -- try it with your 3rd part SIM if you have issues
If you found this useful, or found any problems... please let me know at firstname.lastname@example.org