Death of the Sales Call?

Seth Godin has hit the nail on the head again. I so totally relate to the effects this type of interuption marketing has on any time-challenged businessman. I probably get at least two calls a day from telecoms companies (the unenlightened ones) asking me if I want to save money on my BT account. I haven't had a BT account for more than five years! So perhaps you can understand how angry and frustrated these people make me - and they're so thick. I used to tell them right at the beginning of the call, "I don't have a BT line, I'm on NTL". But do they listen? I've asked them to remove me from their databases. Thay say, "Yes". Do they? No. You'd have thought they would, bearing in mind it would mean they could make additional calls to other prospects, but no, this has never occurred to them. Now I either place the phone down on the desk and carry on working, or let them talk at me, making the occasional acquiescent noise until I decide to inform them I don't have a BT line. The one thing I can't afford to do is sense it's a sales call and immediately wish them a hasty goodbye, because I did that many years ago and it turned out to be a prospective client who rightly got upset and terminated the call. It seems there is no satisfactory way of dealing with these unwanted calls in order to minimise wasted time. So if any of you have any bright ideas for dealing with these sales dinosaurs I'd love to hear from you.