The UK's first trial of mobile IPv6 is suffering technical delays as the operator struggles to make it work, though that's still impressive when the competition can't work out why they should even bother.

Mobile phones themselves have supported IPv6 for the last five years or so, but network operators have almost nothing to gain by deploying it, and a great deal to lose. One UK operator is inching towards trials, and all accept that IPv6 is going to be essential to their business, they're just not very keen to be the first to make the switch.

IPv6 was mandated by the original 3G standards, but those got tweaked when it became clear that v4 could be bodged into working. That bodging now connects IPv4 addresses to billing records and content filtering systems, making the shift to v6 even more complicated. Which is a shame when it’s the mobile networks who will most-likely need the additional address space IPv6 provides.

Today's mobile operators don't provide real (internet) IP addresses to their users - customers of a single network operator will share two or three internet IP addresses between millions of users. Network Address Translator (NAT) boxes issue local IP addresses and route connections from handsets to the internet, conserving address space with the happy side effect of making it impossible to establish connections from the internet to a mobile phone.

Connections between handsets behind the same NAT (and thus with the same operator) are, theoretically, possible, but operators don't allow them. A similar restriction will be applied to IPv6 - the technology will put mobiles on a par with home computers in that anyone on the internet will be able to connect to any mobile phone, but until mobile firewalls are properly established the operators will likely bar such interaction.

That bar won't last forever. As machines want to talk to machines the idea of polling - where the networked device constantly pings a remote server - fails to scale, so incoming connections will be necessary despite the attendant security issues.

Today's network operators really aren't thinking that far ahead. Few of them have any plans for IPv6 at all, and those that do have other things to worry about. The IPv4 address allocated to the customer is also used to measure the data flow, for billing, and to manage the filtering requirements as well as any special billing options (such as free access to specific services for certain tariffs). Changing to IPv6 means changing all that, but it also could mean giving up control over the allocation of IP addresses entirely.

Cisco is now saying it expects to see 50 billion devices connected to the internet by 2020, which is a lot of IP addresses. One of the important capabilities of IPv6 is the ability for a mobile network operator to sell wholesale access to a provider, who will issue their own IP addresses (dynamically or statically) to their own customers. That's great from a network point of view, as long as you're not relying on IP addresses for billing and content control.

But managing, and (more importantly) measuring, access to devices without knowing their IP addresses is challenging for the most advanced of networks, which is what's caused the latest delays though all parties tell us they're confident the trials will be going ahead soon.

The smartphone in your pocket probably already supports IPv6, and from July 1 the network interconnect will support it too, but unless the operators get moving mobile will be the last vestige of the 20th-Century internet. ®