A few years back, there was an episode of Seinfeld where Elaine wanted to change her phone number, only to find that her new number used a different area code and marked her as a new New Yorker—if people even recognized the number as a Manhattan one at all.

The Internet is now in the same sort of situation.

When the Internet was first created in 1978, researchers made space for 4.3 billion devices, figuring that would be plenty. Consequently, when they started handing out IP addresses (i.e., "192.0.2.1 ") to organizations, they did it in big batches—as many as 16 million at a time. Who cared? There were plenty.

But in this age of ubiquitous smartphones and tablets, plus the cloud, printers, thermostats, sensors and the other Things that make up the Internet of Things, the Internet is running out of space. Officially, it ran out of space in February 2011, when the Number Resource Organization, an industry group made up of five regional Internet provider registries, announced that it had handed out the last of the available addresses.

Since then, the regions themselves have run out or are getting close: April 2011 for Asia Pacific, September 2012 for Europe, September for Latin America, February 2015 for the Americas, and November 2019 for Africa.

So people are doing some pretty interesting things to get addresses, particularly in the cloud. For example, they’re buying and selling addresses assigned under the scheme from 1978, known as IPv4. Those old-time companies that got big batches of addresses? They’re finding those to be some of their most valuable assets. In fact, in 2011, Microsoft paid $7.5 million to Nortel Networks during its bankruptcy liquidation, just for 666,624 Internet addresses—winning out over six other bidders.

The Internet Corporation for Assigned Names and Numbers (ICANN) is also working to recover blocks of unused addresses and distribute them in smaller blocks, but that’s getting more difficult; the organization is now down to 10 million or so available addresses. “Redistributing increasingly small blocks of IPv4 address space is not a sustainable way to grow the Internet,” says Leo Vegoda, Operational Excellence Manager at ICANN.

More recently, registration organizations have taken to using addresses from different regions, just because they are the only addresses those organizations could obtain. For example, Microsoft is assigning addresses from the “global” pool for its Azure cloud service, which means various Internet utilities were telling users that their information was located in another country, based on the IP address with which the data was associated. This led Microsoft to assure users that their information was really, truly, in the U.S. of A., just like Elaine had to explain to people that, no, she hadn’t moved to New Jersey.

There is a way to solve this. In the same way that some regions require everyone to use an area code when dialing even local numbers, there’s another kind of Internet addressing system. Developed starting in 1993, IPv6—as opposed to the current IPv4—provides 3.4*10^38 Internet addresses. That’s 340 undecillion (we think) or, according to PC Magazine, 340 trillion trillion trillion addresses. Since this is more than, say, the number of grains of sand on Earth, researchers feel pretty secure that IPv6 will last for a while. Equipment that uses IPv6 has been available since 1999.

So what’s the problem?

The problem is, people generally don’t want to go there. Sure, some of it is inertia—they just don’t want to move from 192.0.2.1 (for IPv4) to 2001:db8::1234:ace:6006:1e (for IPv6). But there’s more to it. Users may need to upgrade or replace hardware and software, such as operating systems or routers, to use IPv6. “Everything that touches IP packets must be upgraded,” writes Iljitsch van Beijnum in Ars Technica. “And that's pretty much everything with an Ethernet port or an antenna."

In particular, not many security products support IPv6, and there is concern that hackers are just waiting for the opportunity to leap on it. While IPv6 itself has many more features built in, it’s lacking many of the tools built to support IPv4 over the decades. And speaking of that, the homegrown IP management tools that many corporate network administrators have relied on to manage the relatively small number of IPv4 addresses just aren’t going to cut it for the much larger number of IPv6 addresses.

Some companies are, however, bowing to the inevitable and migrating to IPv6. On June 6, 2012, the Internet Society held the first World IPv6 Launch, intended to help persuade user organizations, Internet service providers, and developers to support IPv6. And it’s been held since then. Slowly, slowly, providers are starting to fall in line. “Global IPv6 traffic has grown more than 500% since World IPv6 Launch began on 6 June 2012, and this year—the 2nd ‘Launchiversary’—marks the fourth straight year IPv6 use has doubled,” the Society describes on the World IPv6 Launch website. “If current trends continue, more than half of all Internet users will be IPv6-connected in less than four years!”

Goody. But right now, there aren’t very many. Yes, the Internet Society says 242 carriers and more than 20,000 websites support IPv6. But only about 20 percent of the world’s networks support IPv6 and, according to Google, less than 4 percent of Internet traffic uses IPv6, and only 13 percent of the Alexa top 1000 websites (the sites that are most used) are reachable by IPv6. For example, Microsoft’s Azure cloud service doesn’t yet support IPv6, though operating systems from Vista onward have. “The foundational work to enable IPv6 in the Azure environment is well underway,” according to the Microsoft Azure FAQ. “However, we are unable to share a date when IPv6 support will be generally available.”

Moreover, as long as there are people who still have IPv4 addresses, devices need to be able to understand them, which means they’ll need various kinds of translation devices that add complexity and slow down performance.

Eventually, pretty much everyone accepts that they’re going to have to migrate to IPv6. That doesn’t mean they aren’t going to drag their feet every step of the way. After all, how many users of Windows XP (which, incidentally, doesn’t support IPv6) do we still have?