Cell phone carriers have seen a huge growth in wireless data usage. The iPhone is selling like hotcakes, and its users generate large amounts of traffic. Not surprisingly, as cellular providers deploy faster network technologies, users generate even more data.

Here’s data from Verizon:

Customers’ demand for more, faster connectivity is pressuring cell carriers to accelerate their timelines for deploying next generation cellular technologies (the so-called “4G” technologies). One of the most promising of these technologies is LTE, Long Term Evolution. LTE will provide much more bandwidth than current 3G cellular system.

Aside from speed, LTE makes a significant change to cellular networks: Voice is now an IP service. With LTE, your handset is a voice over IP (VoIP) device. This eliminates the distinction between the “phone part” of your smartphone (voice calls, SMS, voicemail), and the “Internet part” (email, web, games, etc). In other words, your phone will need an IP address all the time, even just to receive voice calls.

Independently, the number of cellular subscribers is increasing rapidly. According to the United Nations, more than 40% of the world population has a cell phone:

One research company predicts there will be 5.2 billion cellular subscribers, worldwide, by 2011. Another firm estimates 2 billion new cellular subscribers by 2013. If even a small fraction of these are using 4G, e.g. IP-based, communication, it will place substantial strain on IPv4 address reserves.

The problem, of course, is that we’re running out of IPv4 addresses. The IANA pool will most likely be depleted by the end of 2010. This has led many people to wonder if LTE deployments will require IPv6. Now we have an answer: Yes.

Verizon has posted specs for any LTE device that will be permitted on its LTE network. IPv6 support is mandated. IPv4 is optional. That’s quite a statement, since IPv4 traffic currently dominates the Internet.

A few relevant quotes from Verizon’s spec:

“The device shall support IPv6. The device may support IPv4. IPv6 and IPv4 support shall be per the 3GPP Release 8 Specifications (March 2009)”. (section 3.2.4.1)

and

“The device shall be assigned an IPv6 address whenever it attaches to the LTE network.” (section 3.2.4.2)

IPv4 support appears optional: “If the device supports IPv4, then the device shall be able to support simultaneous IPv6 and IPv4 sessions.” (section 3.2.4.4)

Verizon appears to be trying to conserve IPv4 addresses by disallowing long-term address leases: “If the device supports IPv4, the device shall request an IPv4 address if an application using the LTE bearer requests a data connection using an IPv4 address. Once the application is closed, the IPv4 address shall be released by the device”. (section 3.2.4.3)

I’m curious how this will affect handset manufacturers. Windows Mobile and Symbian (used in Nokia phones) already support IPv6. Google is working on IPv6 support in Android. The iPhone and Blackberry don’t currently support IPv6. I’m curious if version 3.0 of the iPhone OS will add IPv6 support.