Ten of the UK's ISPs have voluntarily signed a code of practice that binds them to providing full and open access to the internet – but three companies have decided not to sign.
The code, which states that its signatories must offer open and full access to the net, not prioritise traffic to its own products or bar access to legal content, is currently backed by BT, O2, TalkTalk, Sky, Be, Kcom, Giffgaff, Plusnet, Tesco Mobile and Three.
There are some exceptions to the open access rule – for example, if ISPs are required to block access to a site by court order (as has happened with The Pirate Bay).
ISPs are also not stopped from bringing in data caps for heavy users, and are allowed to offer parental blocks to restrict access to X-rated web content.
If any ISP involved is found to have breached the code, it will face the Broadband Stakeholders Group (BSG), made up of Ofcom, other ISPs and media companies.
Conspicuous in their absence from the list of voluntary signers are Virgin Media, Everything Everywhere and Vodafone.
But if this code purports to offer fair and open access to the internet to everyone in the UK, why wouldn't they sign up?
Virgin Media, for one, thinks that the code needs a bit more work because the language used in the documentation leaves it open to interpretation by the kind of people who are up to no good.
A Virgin Media spokesperson said: "These principles remain open to misinterpretation and potential exploitation so, while we welcome efforts to reach a broad consensus to address potential future issues, we will be seeking greater certainty before we consider signing."
But rest assured, it's not about to start limiting its users' access to the internet: "We have no intention of discriminating or treating data differently on the basis of who owns or publishes it."
Vodafone is concerned that the wording of the code means it would have to offer a confusing message to its customers.
A spokesperson said, "These plans offer internet access to smartphone and dongle users, but under the code we would have been unable to use the phrase 'internet access' to describe many of the services enjoyed by customers.
Everything Everywhere has also decided not to sign, explaining that it is not convinced that the web is ready for such a code.
"As the market and content delivery models are still evolving, we believe it is too early to know how a code of this type will affect customers' internet experience, but it is something that we will continually review," a spokesperson told us.
Like Virgin Media, it was keen to stress that it wasn't on the side of a censored web, adding, "We support the principle of the open internet and believe transparency is the way to achieve this."