The United States could run out of unique Internet addresses to assign to new devices by the end of next year, a telecommunications official said on Tuesday.
Internet Protocol version 4, known as IPv4, provides the dominant architecture for the Internet. It requires devices to have unique identifiers, known as an IP address, but it only has space for 4.3 billion of those addresses.
The recent profusion of mobile devices like Research in Motion's BlackBerry and Apple's iPad, and the expansion of Internet services to more homes have quickly depleted available addresses.
An upgrade to the Internet's main communications protocol with more space, called IPv6, is available, but adoption in the United States has lagged behind Europe, China and other countries.
There's no reason a new device on a mobile network should be given it's own IPv4 address.
On the 3G mobile network I use (outside the US), each device gets a 10.10... private IP. Traffic then goes through several hops of the private network before coming out into the internet with just a handful of public IPs for the many thousands of customers.
This causes it's own problems (for example, breaks OpenDNS or anything that assumes one user = one IP) but doesn't waste IPv4 addresses. No reason why the US mobile networks, and even regular ISP's, can't do the same.