Despite the worldwide interest in Global IPv6 Day the three main U.S. mobile carriers are still a way off a smooth transition to the new protocol.

The majority of websites today support Internet Protocol version 4, which is running out of individual addresses for users and devices to connect to the Web. This is due in large part to the massive proliferation of Internet-capable smartphones and other mobile computing devices around the world. Hence the need for IPv6, which supports an unimaginably vast number of new available addresses.

Verizon Wireless appears the most advanced in terms of getting new devices and networks to support IPv6. The operator mandated that devices support IPv6 as part of its original deployment plans. The operator now has several LTE smartphones and data cards on the market.

Verizon spokesman, Jeffery Nelson, says -- in an email reply to questions -- that the CDMA operator intends to transition users to IPv6 as they upgrade to the faster 4G network. "This is a going-forward opportunity, with 4G LTE," writes Nelson.

Sprint Corp. (NYSE: S), meanwhile, says that planning is underway to enable IPv6 on its wireless network in 2012.

AT&T Inc. (NYSE: T) has not yet replied to LR Mobile's questions about its IPv6 plans. The operator's CTO, John Donovan, however, says in his blog that AT&T has been working on its "multi-year" IPv6 transition since 2006.

"I believe that the vast majority of customers will see little or no impact as we transition to IPv6, due to the extensive preparation by key industry players, including AT&T, in advance of the transition," he writes.

Any operator work on IPv6, however, is for nought if device vendors and operating system developers don't build support for the new protocol into their code.

Google (Nasdaq: GOOG)'s Android has had IPv6 support built-in since May 2010. See the Living With IPv6 blog for details on this. [Ed note: Might help explain Verizon's love of 4G Androids.]

Apple Inc. (Nasdaq: AAPL) brought IPv6 support to the iPhone with iOS 4 in 2010.

— Dan Jones, Site Editor, Light Reading Mobile