Path: utzoo!attcan!utgpu!utstat!jarvis.csri.toronto.edu!rutgers!tut.cis.ohio-state.edu!netsys!vector!telecom-gateway From: cmoore@brl.mil (VLD/VMB) Newsgroups: comp.dcom.telecom Subject: Re: NXX, N1X, N0X, ... Message-ID: Date: 8 Jun 89 14:30:56 GMT Sender: news@vector.Dallas.TX.US Lines: 7 Approved: telecom-request@vector.dallas.tx.us X-Submissions-To: telecom@eecs.nwu.edu X-Administrivia-To: telecom-request@vector.dallas.tx.us X-TELECOM-Digest: volume 9, issue 191, message 7 of 9 N means any single digit EXCEPT 0 and 1. X means any single digit, to INCLUDE 0 and 1. Until 1973, area code-prefix combinations were of the N[01]X-NNX form. In July 1973, area 213, which includes Los Angeles and which has since split to form area 818, went over to NXX prefixes (in other words, it allowed for new prefixes of the form N0X and N1X), so that for the first time some 3-digit numbers could serve both as a prefix and as an areacode.