Samsung introduced the controversial Region lock with its Galaxy Note 3 phablet and that caused quite a stir – the idea of being unable to use your unlocked device with some SIM cards sounded most unpleasant.
Samsung quickly clarified that this Region lock has been implemented to stem the grey market imports and that it goes away if the first SIM card you use is from the region you bought the device from. After that you can pop in a SIM card from a different region and it should work as expected.
It turned out this wasn’t quite all there is to it, though. Samsung Germany added the additional clarification that you have to use the SIM card from the correct region to make at least 5 minutes worth of voice calls (it doesn’t matter if it's incoming or outgoing calls).
It doesn’t have to be a SIM from the country where you got your Note 3 either, what's important is that a European Note 3 does 5 minutes of voice calling using a SIM from a European carrier (here "Europe" refers to the EU and the European Economic Area, not the geography term, see below).
If you're still having problems with the Region lock, you can visit the regional Samsung Care center to have it deactivated. You can call the center at €0.60/minute from a cell, €0.20/minute from a landline, but it's not clear if the actual unlocking will cost anything and if yes, how much.
Note that the Region lock is implemented in the Android 4.3 software that many Samsung phones are receiving at the moment, including the Galaxy S4, S4 mini, S III and Note II. So, keep that in mind before you hit Update.
If you already have and for some reason the official unlock method isn't working (and you can't visit a Samsung Care center), you can also go the XDA route if you have a rooted phone.
Countries in the European Economic Area (EEA):
Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Liechtenstein, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania , Slovakia, Slovenia, Spain, Sweden, UK, Switzerland, Croatia
Albania, Andorra, Belarus, Bosnia and Herzegovina, Macedonia, Moldova, Monaco, Montenegro, San Marino, Serbia, Vatican City