About #7 (Each country calling code corresponds to exactly one country) and Russia, Kazakhstan. While it's true that +7 corresponds both to Russia and Kazakhsta

About #7 (Each country calling code corresponds to exactly one country) and Russia, Kazakhstan. While it's true that +7 corresponds both to Russia and Kazakhstan, following 3 digits uniquely identify a particular country (e.g. +7 701, +7 702, +7 777 are Kazakhstan, +7 499 is Russia). So for this case you can distinguish between those countries, you just have to use a big database of longer prefixes. If this is important for software, of course. Maintaining that kind of database might be hard.