Remember when telephone companies ran out of phone numbers and forced us all to dial 10 digits to make a call?

The Internet is now in a similar bind, the Wall Street Journal reports. This week, the Internet Assigned Numbers Authority will dispense its last Internet protocol addresses to regional Internet registries. Once these registries distribute the addresses to local network operators, there simply won't be any left. IP addresses are those four numbers ranging from 0 to 255 and separated by dots that uniquely identify devices connected to the web and allow them to communicate with one another.

The current "IPv4" address system, which permits 4.3 billion possible addresses, was developed over 30 years ago, when no one foresaw the web's widespread adoption or the proliferation of web-enabled devices. The plan is to migrate to a new system--"IPv6"--which was introduced in 1998 but is rarely used. How many addresses does IPv6 offer? Oh, just 340,282,366,920,938,463,463,374,607,431,768,211,456. In June--during a 24-hour period dubbed World IPv6 Day--web titans like Google, Facebook, and Yahoo will test out their IPv6-compatible servers.

Obviously, we should be excited to celebrate World IPv6 Day. But, as we stand at this digital crossroads, how should we feel about the development as a whole? Here are the things to be thinking about:

• Transition from IPv4 to IPv6 Will Be Difficult, says CNET's Stephen Shankland: "Experts expect a years-long transition to move fully to IPv6. During that time, Web site operators, Internet service providers, and others will have to gradually shift infrastructure from handling one protocol to handling both."
  

• No Need to Panic, Though, argues PCMag's Samara Lynn: "IP address exhaustion has been known about for years, and those making up the backbone of the Internet have provisions in place. For most of us using our many devices and technology toys at home, the last IPv4 address will get allocated without any notice."
  

• IPv6 Has Benefits, But Could Be Headache for U.S., notes The Economist's Babbage blog. Babbage says we'll need IPv6's vast universe of addresses as we hurtle toward a future in which every person and object has Internet access. But IPv6 isn't compatible with IPv4, which will make life difficult during the interim period when the two systems coexist:
  

That could mean putting up with interoperability hassles for decades--at least, in the United States ... Being the inventor and earliest user of the internet, America received the lion's share of addresses before today's rules were put in place. As a result, many large companies, universities and government agencies in the United States still have plenty of spare IPv4 addresses lying around unused. The pressure to upgrade has therefore been minimal.

That is not the case elsewhere ... Being one of the last to embrace the internet, China has only one address for every four people. Hence the urgency in Beijing to adopt IPv6 as rapidly as possible. The same goes for Russia, South Korea and Japan.

• How Will Web Cope Until IPv6 Is Adopted? asks Gizmodo's Adrian Covert: "The Internet will get by on a diet of repurposed and recycled IP addresses ... If your grandmother's Facebook account wasn't a tell-tale sign that the internet has come of age, here's another."
  

• Will Internet Expansion Temporarily Halt? wonders Dean Takahashi at VentureBeat. He explains that in fast-growing countries like China and India, IP addresses are getting gobbled up quickly: "With no addresses left, the internet will not have anywhere to expand. The United Kingdom has begun a campaign urging every web site to make the shift to IPv6."

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Uri Friedman