Why do you get the message that you must first dial "1" before the area code?
When you forget to dial "1" before an area code, a recorded message informs you that you "must first dial a '1' before dialing this number." If the little man in the phone can tell that the number requires a "1" in front of it, why do you first need to dial a "1"?
Grade school teachers must have hated you, Reuben. You're absolutely right: if the switching computer is smart enough to figure out that the number needs a "1" in front of it (in other words, that it's a long distance number), it's smart enough to put the call through. Same deal right after an area code split. If you dial a no-longer-local number without putting the new area code in front of it, you get a message telling you to redial it with the area code first. But the computer is perfectly capable of figuring out what number you were trying to get and put the call through. It just doesn't want to — or rather, the phone company geniuses who program it don't want to. On the contrary, they're trying to teach you a lesson so next time you'll do it right.
Sounds a little schoolmarmish, but the phone company doesn't have much choice. "One-plus" dialing was implemented to make more three-digit combinations available for area codes and local exchanges. (Previously the middle digit in all area codes had to be a 1 or a 0 so the switching computer would know a long distance call was being dialed.) Now it's possible for Berkeley to have the area code 510, and for each area code in North America to have a 510 local exchange. But — this is the important part — not right away. First the phone companies have to pound the idea of one-plus dialing into the consuming public's head, so when Nick in Newark calls Berkeley long distance information, 510-555-1212, the call doesn't wind up at Joe's Pizza, 510-5551, to the consternation of Joe. Thus the message.
Eventually, of course, 510 will be assigned for local use, and if you forget one-plus you won't get the recording, you'll get Joe (or whomever). The phone company just hopes you'll have gotten the idea by then.