Normally, the video over your newly installed 32 megabit broadband connection is super-smooth. However, this morning, newscaster Chantelle Houghton's face looks like a Monet slideshow, the audio is distorted and choppy, and the stream occasionally freezes entirely for several seconds.

Ah well, you shrug – network problems are not unknown. You shut down the stream, polish off your cereal and decide to check your personal e-mail before heading off to work. Thirty-seven unread? That seems like rather a lot. And most of it seems heavily commercial, albeit a cut above the usual level of spam – most of the messages are correctly spelt, and many of them use your real name.

Among all of this dross is an e-mail from your ISP. You open it, thinking that perhaps they'll be apologising for a failure in the spam filter. But in fact it's informing you about certain "upgrades" to the service.

The first seems to be the opposite of what you expected – a "spam elimination measure", whereby companies will have to pay a penny per message to get guaranteed e-mail delivery and bypass spam filters. "This," says your ISP, "will allow us to tighten up the spam filtering even further without affecting legitimate commercial email." From where you are standing, this doesn't seem like an improvement.

The second new feature is "enhanced performance for Sky News subscribers", combined with a discounted subscription offer. However, you also notice that the small print at the bottom says "users of other video services may experience degraded performance at peak times". You suspect that this might be the cause of your earlier issues. But you much prefer the ad-free BBC newscast. And you can't switch ISPs; it's a big hassle, and anyway you are on a 12-month contract.

What's gone wrong? Your service provider has abandoned the principle of network neutrality – that a particular service should be treated the same no matter who provides it. Unlike traffic shaping, which prioritises time-sensitive services such as internet telephony over less critical ones like music downloads, lack of network neutrality means that you no longer have a free choice of internet telephony service, as your ISP slows down or even refuses to carry the traffic of providers who haven't paid.

Although ISPs in the UK currently maintain neutrality, the issue is becoming a big one in the United States, with Senate hearings being held amid the clash of lobbyists. Service providers want network neutrality to be the law. Telecommunications infrastructure providers on the other hand, frustrated that their stock is clapped in irons in the hold while that of Google and other service providers admires the view from the crow's nest, are planning a mutiny. They want a piece of that $2 billion-per-quarter treasure chest.

Ed Whitacre, the chief executive of SBC, a large telecoms company, summarised their frustration last year when he said: "Why should the service providers be allowed to use my pipes? The internet can't be free in that sense, because we and the cable companies have made an investment and for a Google or Yahoo! or Vonage or anybody to expect to use these pipes for free is nuts!"

So should telecoms companies be allowed to discriminate? The success of the internet has been based on its ability to enable innovation. Innovation relies on a level playing field – where all companies have equal access to consumers. Only then can the market decide which service it prefers. Network providers cannot be allowed to be internet toll collectors, who decide what new and innovative ideas are allowed to reach the consumer, and how much you have to pay for your new site to get a fair shot.

When America sneezes, we catch a cold. So the next time your internet service provider sends you a e-mail talking of service improvements, special deals and "priority access to content", read the small print. You may find you are no longer getting what you paid for.

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Gervase Markham works for the Mozilla Foundation, a non-profit organisation dedicated to promoting choice and innovation on the internet. His blog is Hacking For Christ

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