The standard is called Dual-Stack Light, which means you are getting a native IPv6 adress and your IPv4 traffic runs through a carrier-grade NAT. This is necessary, because the cable-providers here in Germany came to late to the Game and got to little IPv4 Chuncks. For normal users this is a good solution, when the NATing service is stable enough. (Sometimes the server is down and you are forced to IPv6 only..) But throug the carrier-grade NAT, you can not run your own services, like a teamspreak server etc.