Roll up! The market for high-speed internet exploded with barrow-boy excess last week, thanks to one deal that sounds too good to be true. Opinions are divided over whether Carphone Warehouse’s offer of “free broadband for ever” to its 2.6m TalkTalk fixed-line phone customers is genuinely free, but, wow, has it shaken up the competition.

Out of the blue, Carphone triggered a price war in what was already a noisy bazaar, echoing with spivvy promises. Since April 1, most internet service providers (ISPs) have passed on BT Wholesale’s miraculous upgrade of ADSL broadband by offering a free bandwidth boost, described as to “up to” 8Mbps — 16 times faster than the 512kbps that was such a relief from dial-up. Overnight, thousands of surfers found themselves staring a gift horse in the mouth, even though some 8Mbps horses now cost £21 per month and others £41.

Nice, but the drawback is that nobody can actually download at 8Mbps, or anywhere near. The headline figure is pure fantasy because data delivery rates depend on technical factors such as distance from the exchange, line contention, quality of your household wiring, and whether you restarted your router properly.

As a result, BT itself estimates that only 4 out 10 Britons are able to receive “up to” 6Mbps, and only six out of every 100 receive “up to” 8Mbps. But hey, says Ian Livingston, chief executive of BT Retail, 93% should be accessing “up to” 2Mbps, which will happily stream BT’s upcoming on-demand television service, missing the point that the dangled carrot in each case is qualified by the weasel words “up to”.

ISPs are prone to blame the regulator, the Advertising Standards Authority (ASA), which insists all broadband adverts should include the “up to” cop-out. Wanadoo was among the first to market with “up to” 8Mbps, but in February rivals, ironically, had an ASA complaint upheld after the ISP implied the service was widely available. “If you are advertising that everyone can get 8Mbps and they are not, it could be misleading,” said ASA spokesman, Matt Wilson.

In reality, the fastest possible download rate is closer to 7Mbps, once some geeky admin overheads on your web pages have been deducted. That’s like Virgin Trains promising to take you from Glasgow to London, but dumping you at Milton Keynes.

BT’s line test on my former BT number said that it should be able to support a potential ADSL Max broadband line rate of “5.5Mbps up to 8Mbps”, which sounds impressive, but is as precise as a US Air Force bombing raid. Even this vague promise is only “indicative”, BT says, and accurate only to “about 10%”.

Livingston points out that, whatever the true rate, subscribers haven’t been asked to pay any more for the extra speed — the gift valued at “up to” 6Mbps — despite which, you could be paying the same as the smug b oater with the horrible curtains along at number 11, for half his speed.

What about people left with less than today’s basic 2Mbps? They may never be able to keep up with the digital Joneses, since Livingston admits his company is “some way from offering 2Mbps to the remaining 7% of homes”.

Meanwhile, ADSL broadband remains a slippery technology, and the folly of giving away whopping upgrades that resulted in broken promises overnight is a marketing bungle of the first order. “Up to” 8Mbps could mean no service whatsoever — and survive the trade-description laws.

The ASA should reword its requirement for ISPs to preface every speed with their get-out clause. Offer us instead “more than 2Mbps”, say, or “between 4Mbps and 8Mbps”. The ASA says it is complaints-led, so direct yours to: www.asa.org.uk.

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