Not just old movies, when I started here at Purdue we had two 'exchanges' serving campus, the 749- and the 494-. If your number started with 749 then anyone on campus could call you dialing only the last four digits. If you had a 494 number then the last five had to be used. The exchange was/is on campus, but run by GTE (now Verizon).
Tim
[TELECOM Digest Editor's Note: Ah, so you must be a newcomer around West Lafayette, then. Back in the 1950-60's, Lafayette and West Lafayette had just gone dial and to reach Purdue University there were two ways to do it: From any phone in the Lafayette or West Lafayette area one dialed '90' from any (off campus) phone to reach the Purdue operator, or you dialed '92' plus five digits if you knew the extension you wanted. Furthermore, because the town was GTE rather than Bell System, with the advent of 'area codes' the area was not in the (logical) 317 area code. Instead, (in Chicago area at least) to reach someone on Purdue campus we dialed the long distance operator ('211' in those days) and asked our operator for 'Lafayette 90' or 'Lafayette 92-xxxxx', or Lafayette seven whatever digits for a non- campus place.
When I went to West Lafayette once in 1956-57 or thereabouts for a debate tournament I promised my mother I would call home when I was there. I went into the student union at Purdue to use a payphone and when I dialed the operator to ask for Chicago, Area Code 312, xxx-xxxx the operator rudely cut me off after hearing the 'area code 312' part of my request to inform me, "We do not go by area codes here, just the number in Chicago is all." Inward must have been really busy that day, because I heard ringing (of the inward operator) at least 25 times for close to five minutes when the Lafayette operator cut the connection and said to me, "I am sorry sir, but Chicago is not answering right now ... would you try again later, please." PAT]