I've seen a lot of people wonders what GEN means, and thus asks for a code request. Since code requests are not allowed in this forum, and I understand most people is able to generate the code by themselves with a little knowledge, I've decided to post a little explanation of what does GEN mean.
I hope this helps a little and reduce the code requests, and the quantity of users banned. Please forgive me for the gramatical mistakes, english is not my mother tongue.
I've posted this same answer on the general forum, and a little explanation of GEN is on the FAQ section, but most people does not seem to make a search before posting, they don't even read the rules.
If moderators find this a little helpful, maybe they will make it a sticky.
My best regards and best of lucks in the unlock process
What GEN means:
When a provider locks a phone to a certain network (or nokia for the sake, sometimes I understand they do), they use a piece of hardware called dongle.
That dongle has a serial number in it and defines a part of the dct4 algorithm, the mathemathical algorithm that results in the seven codes that calculators give to you when you ask them to calculate.
You can try to see that change changing the GEN variable. You will see that almost all the codes seems the same, but the first numbers of the codes slightly change.
Now, when you have to calculate the right code for you, you must use the same serial number that was used to lock the phone. The denominations like v2, GTCL-001, Prodigy, ONE, Original, etc, they all denominate a serial number. We call it GEN, but sometimes we call it box, boxSN, etc.
To know which is the right box to your phone, it is good to sometimes post a new thread on the forum, because probably someone already generated a working code for that provider and model and knows which is the serial that works.
For a basic rule of thumb or as an starting point, type *#0000# on your phone. If the firmware is old, '03 and backwards, let the GEN, or boxSN on v2, or sometimes GTCL-001, depending sometimes on the model (for example, the majority of 1100s are locked with GTCL-001, 33552, but newest models are using other boxSN, like Original or even asic6).
If your software is newer, '04 and forward, probably Original will work, but there is not a constant. For example, newest 1100s as I said before are using Original, sometimes ONE, even asic6 boxSN. Virgin, as posted by Mr. Gieffel, is using a specific box, 32811 if my memory does not fool me.
So, in asbtract:
When generating a code, there are four variables. Three of them are static, while one is dynamic:
a)Imei: that is a static variable, every phone has a different and unique imei.
b)Network code: static variable also, every provider has a unique network code.
c)asic type: static variable. Depending on your phone, it's gonna be one and just one asic type. Too see which ASIC is your phone, go to http://nokiaport.de/unlock/asictype.php
d)GEN, or boxSN: dynamic variable, because there is not rule to know which dongle was used to lock the phone.
The best way to find out the appropiate boxSN to use, is doing a search on the forum by your phone, the network that it is locked to, etc., because it's probably already there (as an example, this question and explanation has been made several times before ), or in case you do not find anything, posting a new thread.
Hope this helps a little!