Unlocking the locked ones

Few days back, I got a locked N73 and the main challenge was to unlock it.

N73 is a different model of Nokia and can not be unlocked as easily like unlocking Nokia's old models like 6230i etc.

Most new generation Nokia cell phones are using Symbian OS and since I am very little exposed to this OS, I could not do anything to log on this phone and check any loop holes to unlock.

So, I searched on the Internet and came across a site on www.imserba.com at http://www.imserba.com/forum/showthread.php?t=110552&page=2.

Its indeed very interesting forum and there I found out a techie word "unbranding".

I followed the instruction mentioned on this forum and tried to unlock my N73 but it seems my N73 is as adamant as Sissie that it just does not want to unlock/unbrand...

I contacted the forum creator "joneywalker4u" and he suggested few additional steps to perform. This evening, I performed those steps but the phone is still in Sissie mode...

Below are some of the pictures of this process for "joneywalker4U" to review the process and suggest me next method...

Above screen appears as a result of *#7370# to reset the phone. It then asks for the security code and then resets the phone.

After reset, the phone boots with original O2 card and since this SIM does not have a roaming activated, it failed to register to my local network.

NSS generates some messages as shown on "SCAN".

Phone Info on NSS generates above screen. You will notice the product code, HW version and other details as I issued 'read' after changing the product code.

I later used product code 0543843 derived from a friend's unlocked N73 and then wrote that product code in the phone.

 
NSU detected the phone and suggested the latest firmware version to be 4.0750.31.2.1. Since I did upload this firmware earlier, current and update versions are same in above screen shot.

As I did erase earlier version from the cache, the firmware was downloaded from Nokia site and then on the phone.

After downloading the firmware, NSU updated the software on the phone and finally produced below screen shot. 

I then replaced original O2 SIM card with my local Airtel one and rebooted the phone with a hope that the phone would accept this SIM... But unfortunately, this N73 is no different than Sissie as it still wants to remain unlocked with a message "SIM card not valid!"...

I will write to JoneyWalker4U again and send him this link so that he can suggest something.