I think SLAs should always be supplied with a service and those that do not offer one, miss a vital point about the service infrastructure they've put in place. There's not one single, ideal level of service that everyone should be striving for with IP networks. We know this because no two applications have exactly the same network requirements, hence consumer A will have subtley different requirements from consumer B. End consumers *may* want a generalist service, that can do a bit of everything, but as an ASP would your applications have the same network requirements as a video/VoIP provider? Would someone doing backup services share these requirements? There's a vast (and growing) space for differentiation of services and this can only occur with valid SLAs.

From a legal perspective:

If I sell someone transit for a month, then the service is "down" that month, and heh I didn't offer an SLA. Then you still have to pay me for the service and I pay you nothing back. OK I'd lose my customers, but: I'd be considerably richer having sold bandwidth for a month and not used any myself, than I should be considering I've just ripped my customers off. That's why the SLA exists. It is a necessary part of the contract that defines the quality of the product to be sold. Toby All-- In a perfect world, your provider says the service is always on, the service is always on.  In the real world, we have to deal with outages -- some kids vandalise a phone box, new tech trips over some cables, some idiot telco misimplements MPLS and brings your service down for a day.... These things happen, and sometimes we all just have to suck it down and deal with it.  But if it happens continuously, you have to ask your provider for some assurance that it won't keep happening.  This is what SLAs are for. In my experience, a company that delivers reasonable levels of service has no need for SLAs with their clients.  The service is up, everybody is happy.  SLAs are like your parent telling you to do the dishes again "and get it right this time, or else you go to bed with no jell-o!" Which s why, in looking for a vendor, I ask for an SLA.  If they have one as a standard offering, then I know that they've messed up a lot in the past, and will probably be messing up more than I like in the future.  It's like the kid who never did his homework coming up to the teacher on the last day of school asking for extra credit.  NO YOU FOOL!  You should have done it right the last 180 days! Anyway, just my thoughts.