hi i have a nokia 7600 which i bought on the 3 network i unlocked it myself by entering the unlock code i was able to find on the internet and it worked 100% i use an 02 chip in the phone at present and have had no problems but recently undo resriction comes up now and again and it wants me to put a code in so i turn off the phone and turn back on and it is back 2 normal until 2/3 weeks down the line it randomly does it again the phone is 100% working otherwise network coverage is excellent etc its just annoying as u have to keep checking the phone just in case it does say undo resriction because than no one can get through to u if u now wot i mean
aint had no luck it said can not be restricted or something like that by the way how do u know wot box serial to use? i just used the same one as when i unlocked my phone originally
i use software so it tells you the box codes anyway, i tend to search for them on the net when the phone comes out it only has the one, then they get more and more variations making it more difficult to unlock another thing you might be experiencing problems is that the 7600 i believe is a 3g phone and that sim card you have put into it is a 2g sim card, which sometimes causes problesm, lots of stuff on the net about that