I travel a lot and always buy a local prepaid sim card wherever I go, to pop into my Galaxy Note 2. I've never had a problem. I'm now looking to upgrade to the Note 4, since I am currently in the USA and it's cheapest here. There are various versions available on Amazon - 910C, 910A, etc. I have seen posts that the letter refers to the region (and they have different CPUs as well), but Africa is not listed at all (I live in South Africa) and I just want to make sure that the phone I buy will work pretty much everywhere. For the unlocked phones that are available on amazon, the "A" seems cheaper than the "C". Is there any reason I shouldn't buy the "A"?