An entity that provides IP service to a customer base, either in a closed environment (no external world view) or open, world connected Internet service. At a minimum this would entail a bilateral aggreement with another provider to exchange routing information between the two. Seems that the above is a sufficient definition. It's either too much or not enough: - "An entity that provides IP service to a customer base" in itself sufficiently defines an internet (lowercase!) service provider. - Even though a particular customer of a certain internet service provider may have access to most of the Internet (uppercase!), certain parts of the Internet may well be blocked to him due to AUP constraints. - Exchanging of routing information is pretty useless if it isn't accompanied by exchanging of traffic. In fact it's *only* the latter that determines whether a certain internet service provider is an Internet service provider. - One of the parties in the last sentence must have Internet connectivity, otherwise we're still speaking of internet service providers only. So I would propose the following wording: An entity that provides IP-based services to a customer base, in a closed group of networks or - as far as possible within Acceptable Use Policy constraints - to the Internet at large. At a minimum the latter would entail a bilateral agreement with at least one Internet-connected service provider to exchange traffic and routing information between the two. Piet