I would direct anyone looking for the skinny on Erlang to look for a white paper on the subject. Perhaps I’m just lazy… Also couldn’t hurt to look up poisson(sp) to compare.
Anyway, the way line vs. trunk works, in my opinion, is that a trunk ties switches together, whether it’s a switch in a network or a PBX at a company’s premises is really unimportant to the definition of a trunk. Trunks are normally not rich in features, and are almost always brought in (In the US) by legacy, T-carrier facilities.
A line on the other hand, connects end users, (stations) to a switch, and most always has a concentrating device between the switch and the customer. Centrex service is provisioned on lines… and there is a trunk to line ratio (such as, three T1s (72 trunks) go in, 96 lines come out). Or something like that.
Hope this helps some.
Lines connect users to networks, trunks interconnect switches.
Trevor, T1 is carrier, DS1 is the service provided, DS0 is the 64k timeslot.