Tony writes:
Not if it simultaneously wants protection from liability for any content that the customer might be sending.
Now that I can fully agree with, although it's not an engineering issue.
ISPs that simultaneously want common-carrier protection from liability AND the ability to finely dictate what types of traffic they will accept need to choose one or the other. Either you screen and restrict the traffic on your network, but you take full responsibility for whatever is passing over it, or you just provide raw bandwidth and you are shielded from any claims of impropriety in the use thereof. You can't have it both ways, as companies like Prodigy have discovered.
FWIW, and not to drag us too far into a legal discussion, but the above is not correct for the United States. In the US, ISPs are not, and never have been viewed, as common carriers. And, as one can see in the on-going arguments made about the possibility that cable ISPs might interfere with content, ISPs in general have strongly resisted being treated as common carriers. They do not want to take on the obligations that common carrier status would bring.
Having said that, ISPs in the US do have common carrier-like protection from liability for content of their customers and others -- but this protection from liability is by statute, not as a result of any common carrier status. Section 230(c)(1) of chapter 47 of the U.S. Code states:
(1) Treatment of publisher or speaker
No provider or user of an interactive computer service [read, an ISP] shall be
treated as the publisher or speaker of any information provided
by another information content provider.
This protection from liability is in no way dependent on what restrictions an ISP places on its traffic. Thus, for purposes of this thread, if an ISP wants to "finely dictate what types of traffic they will accept" they can do so without loss of liability protection.
John