I'm not sure you will be able to update to kit kat. Your phone should update to a more recent version of Android than that though. Have a look in Settings for System Update (not sure exactly where it would be on that version)
Could you please tell me to which version I can update to for sure. So that for now I will update to that version and will try to update to Kitkat later on.
I had a 9100 until recently. I bought it new (deal price) with a sim contract in June 2012, when the S3 had been the new king for a few months. I expected it to come with 2.3, as ICS was only just out. I was very happy to receive a factory sealed phone with 4.0 out of the box.
Roughly 6-9 months later it updated to Jelly Bean 4.1.2. For me that has been the best upgrade ever. It was a joy, and like getting a new phone.
I since bought a Note 3 which came with 4.3, and then came 4.4.2.
Trust me 4.3 was no great shakes over 4.1.2, some extra tabs on the main menu rather than scrolling down. 4.4.2 was a side step, and ruined the smooth running of the phone for many for a while.
The GS2 will only go to 4.1.2 via OTA or Samsung Kies. Trust me you will love it, and you are not missing anything with 4.3 or 4.4.
I am having the same problem, recently bought a secondhand Galaxy S2 with 2.3.3., unlocked and I use Virgin SIM on a monthly contract. I have been unable to upgrade Android. Kies recognizes the phone but does not show any firmware updates. According to SamMobile my model (GT-I9100) goes to 4.1.2. I took it to a mobile tech who tried to flash it with Odin in order to upgrade, but Odin would not recognize the phone. I did a root check and it is unrooted.
The retailer I bought it from says the S2 cannot be upgraded, but I know that's bull. Any idea what might be causing my phone to be un-upgrade-able?