iPhone owners have been kicking up a stink online ever since Monday's announcement of the iPhone 3G S.

Or specifically, since they learned they'd have to pay to cancel their existing contracts in order to upgrade when the handset goes on sale on 19th June.

There's rage on Twitter, online petitions, and forums full of enraged early adopters who upgraded to the iPhone 3G in July last year, and now face either paying through the nose or waiting six months to get the all-new model.

O2 UK and AT&T in the US are taking the brunt of the upgrade rage, but have they really done anything wrong?

As both operators have explained, it's their policy not to let subscribers ditch their contracts just because a sexy new handset has come out.

Last July, they were able to let original iPhone owners upgrade to the iPhone 3G because those original iPhones were unsubsidised.

However, that wasn't the case for the iPhone 3G – upgraders didn't pay full whack last time because the operators chipped in to subsidise the cost. It's no surprise, really, that the operators are standing firm on their contracts less than a year later.

Not that this will cheer those of us who queued up to get an iPhone 3G for the same reasons that we now want to get an iPhone 3G S.

Hence the online rage – I confess to a touch of this myself the other night when writing the story up for Pocket Gamer. But as numerous online commentators have pointed out, we should stop whingeing and either cough up, or wait our turn.

However, the whole farrago does illustrate a problem that's not the fault of the consumers here.

Apple is clearly running a 12-month product cycle (or near enough): the first iPhone went on sale in June 2007, the 3G model came out in July 2008, and now iPhone 3G S is shipping in June 2009.

But you can't buy an iPhone on a 12-month contract. O2 offers a choice of 18-month and 24-month contracts, while AT&T insists on 24 months. The only alternative is to stump up for a pay-as-you-go iPhone.

There's surely an opportunity here for these operators to craft some kind of 12-month rolling contract, for customers who know they're going to want every new iPhone on Day One.

Flexible thinking, in other words. How this fits into the economics of operator subsidies is a challenge for them to tackle – as are any concerns that in countries where more than one operator is selling the iPhone, customers will simply churn between them.

O2 and AT&T might not have done anything specifically wrong this time, but they have a chance to do something right next time round, and avoid angering some of their keenest customers.

Is it greedy to expect to be able to upgrade to a new iPhone every year? Perhaps. But Apple clearly knows there's a demand for it, judging by its annual refresh.

These mobile operators are smart companies who (in theory) are well attuned to their customers' desires. Hopefully a solution can be found that satisfies everyone.