So the iPhone 5 will support 4G LTE... but whose?

That Apple's new iPhone will have LTE seems beyond argument now, but who exactly will get to sup at the font of 4G pleasure? The new iOS smartphone, set for its official unveil on Wednesday this week, is widely expected to follow the new iPad with the addition of LTE connectivity. However, it's also expected to prompt new degrees of 4G confusion, as Apple is forced to make iPhone 5 LTE decisions that will see some users embraced by high-speed data while others are left to struggle on with HSPA+. Even high profile LTE launches in the UK and elsewhere may not be able to follow up with a flagship iPhone 4G to play on them.

The LTE headache isn't a new one for Apple – the company experienced similar frustrations at the launch of the new iPad with Retina Display. The first of the firm's tablets to offer 4G connectivity, Apple's choice of LTE modem meant different models were required depending on whether Verizon or AT&T was your preferred carrier in the US, while those countries with LTE available outside of North America were left out altogether. Instead, HSPA+ was the best on offer, something which prompted a surreptitious rebrand of the tablet itself after Australian regulators – among others – complained.

Apple's problem – though one not limited to the company by any means – is the spray of LTE service spread across different chunks of the spectrum. Modern phonee and cellularly-enabled tablets intended for international use have settled on quadband GSM/EDGE (for voice and slow data) and, increasingly in recent years, pentaband HSPA (for up to HSPA+ data speeds on networks in North America, Europe, and Asia). The gradual roll-out of LTE, however, has been left to slot into whatever spectrum each country (and operator) has to spare.

So, Verizon's and AT&T's LTE runs on different frequencies, and they differ from the LTE UK and mainland European networks are using for their own rollouts. That's different again from LTE in Asia. An LTE iPhone intended to run, therefore, on both main US networks plus LTE in the UK, mainland Europe, and Asia would need to pack support for 700MHz, 800MHz, 900MHz, 1700MHz, 1800MHz, 2100MHz, and 2600MHz, a seven-band radio that only Qualcomm is close to offering (and which, with in the region of 36 LTE bands in use around the world, will still leave some carriers out in the cold).

Nokia, a company that led the way on pentaband 3G radios in its phones, is offering pentaband LTE (800/900/1800/2100/2600) in its new Lumia 920, but even that wouldn't be able to work across all the key carriers. There's no denying that the flagship Lumia is a bit of a tubby proposition compared to what Apple has been doing with the iPhone of late; the Nokia is 10.7mm thick, versus the 9.3mm of the iPhone 4S, and while the floating-lens assembly of the Windows Phone's PureView camera is undoubtedly contributing to the bulk, a bigger radio probably doesn't help either.

[aquote]Hoping for a single phone that handles all LTE is a recipe for disappointment[/aquote]

The upshot? In a marketplace where LTE deployment varies not only by country but often by individual operators within those countries, holding out hope for a single phone that handles each breed of 4G is likely a recipe for disappointment. That's before you even get to VoLTE, or voice-over-LTE, which is in even more fledgling a state than 4G data.

Rumors of the new iPhone supporting LTE are not exactly new, and indeed the addition of true 4G to the smartphone has been expected for some time. Apple frustrated some would-be buyers by failing to include it in the iPhone 4S built for Verizon, though at the time the company said that the power and bulk compromises involved meant that it was a concession it was unwilling to make.

Verizon and AT&T – currently supported by the LTE version of the new iPad – are almost certainly likely to get LTE support on the iPhone 5. Beyond that, it's likely a case of which carriers can offer Apple the right marketing support and which have an LTE network – or imminent 4G plans – worth considering.

Apple's strategy of the past few years, broadening iPhone availability across a number of carriers in each market, may stumble in the face of this LTE headache. The new iPhone 5 will undoubtedly support HSPA+, but those wanting the very fastest data speeds will get a significantly curtailed choice of networks, if they have that choice at all. In fact, though LTE is finally waking up in Europe, data-hungry users may have to wait until the generation-after-this in order to actually use an iPhone on that high-speed 4G.

SlashGear will be liveblogging Apple's new iPhone announcement on Wednesday this week. Join us from 10AM PT (1PM ET; 6PM UK) at for all the news as it's made official!