Unlock Galaxy S4

Follow steps carefully and correctly.

METHOD 1

Dial *#0011#
press Menu then tap BACK
press the Menu again the tap KEY INPUT then enter 1, press OK button
press Menu then tap BACK
Your are now in the SERVICE MODE MAIN MENU

Tap [1]UMTS 
then [1]DEBUG SCREEN 
then [6]PHONE CONTROL 
then [6]NETWORK LOCK
then tap [3]PERSO SHA256 OFF
Go back to the UMTS MAIN MENU by pressing Menu then Back then tap [6]COMMON
then [6]NV REBUILD
then tap [4]RESTORE BACK UP
the device will freeze, black screen, Blue LED Light, Menu and Back key ON. Wait for it to reboot (about a minute).

Your Samsung Galaxy I9505 is now Sim-Unlocked.

METHOD 2

This is what I did. Slightly different to OP.

I did this with my AUTHORISED Sim in first.


1. Dial *#0011#
2. press Menu then tap BACK
3. press the Menu again the tap KEY INPUT then enter 1, (wait a few seconds) it auto jumped into service menu.

4. press Menu then tap BACK (not needed for me)

Your are now in the SERVICE MODE MAIN MENU

Tap [1]UMTS (may auto go into next menu (mine did)

then [1]DEBUG SCREEN 
then [6]PHONE CONTROL
then [6]NETWORK LOCK
then tap [3]PERSO SHA256 OFF

Go back to the UMTS MAIN MENU by pressing Menu then Back (several times) 

then tap [6]COMMON

then [6]NV REBUILD (if this does not work next time)

do [4]RESTORE BACK UP

the device will freeze, black screen, Blue LED Light, Menu and Back key ON. Wait for it to reboot (about a minute).

Your Samsung Galaxy I9505 is now Sim-Unlocked.

Edit: 

When I booted back in with AUTHORISED sim, I had to turn off Mobile Data, then turn it on. 
I then turned off the phone, put my UNAUTHORSIED Sim in, booted back up and NO NETWORK PIN request!

Again, I had to turn off Mobile data, then turn it back on. The UNAUTHORSIED Sim worked!!!