Likewise from a customer view point, if your Telco offers you any form of online billing/reporting system - set them up to warn you of expensive calls or other things you may consider abnormal on the account. It might mean the slight headache of increased email traffic but it could save yourself and your telco a bundle in charges.
BTW all the analogies in this thread so far have been awful ;) I'm not proposing a better one either. (The closest relationship however would be "I have a wireless router, I didn't know my password of kitten was highly guessable, but at the same time you shouldn't have charged me for the 100 gigs of data that my connection did through you because I didn't do it on my computer" and even that has holes in it..)







