Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!usc!wuarchive!texbell!chinacat!telecom-gateway From: nvuxr!deej@bellcore.bellcore.com (David Lewis) Newsgroups: comp.dcom.telecom Subject: Re: Calls With Area Code Prefixes (800 in particular) Message-ID: Date: 30 Nov 89 17:53:13 GMT Sender: news@chinacat.Lonestar.ORG Organization: Bellcore, Livingston, NJ Lines: 51 Approved: telecom-request@chinacat.lonestar.org X-Submissions-To: telecom@eecs.nwu.edu X-TELECOM-Digest: volume 9, issue 540, message 3 of 7 In article , goldstein@delni. enet.dec.com writes: > In article , dgc@math.ucla.edu > writes... > >Can anyone tell me exactly how calls with area code prefixes are > >handled? Previous messages on the handling of 700 calls left me with > >some questions unanswered. I think that there are basically 4 cases: > >1. 1-800 prefix > Two answers on 800 service. Today, they use the "NXX" method. Each > of the NXX codes (i.e., 800-221, 800-222, etc.) belongs to one or > another LD carrier. The local telco simply hands it off. Each RBOC > owns a few of its own, too, for intra-LATA use. "Tomorrow" (R.S.N.), As soon as 80% of BOC end offices are connected to the Signaling System 7 (common channel signaling) network. At least, that's the latest FCC ruling. > there may be a huge telco-owned collective data base indicating which Oh, please don't say "collective" in the same breath as "telco". That always makes people think of the other word that starts with "coll" -- "collusion". A more accurate description of 800 Database Service (800 DBS) is that there will me 800 databases owned by each telco, with the appropriate information duplicated. > carrier carries each 800 number. So you will be able to switch > carriers without changing 800 numbers. The problem is delay: There's > a finite time it takes the telco to send the lookup request through > the SS7 network to the data base engine (SCP). It delays call > processing by a few seconds. Other than that, the technique works > well. If your phone subtends an end office which is SS7-connected, the delay is actually less than a second. Delays only really pile up if the end office can't send a query directly to the database, but has to hand off the call to a tandem via MF (Multi-Frequency -- inband) signaling. Then, it gets really bad. That's one large reason why the FCC mandated that the BOCs can't switch from the NXX method to 800 DBS until 80% of end offices (actually, it may be 80% of end office lines, but the economics fall the same way) are SS7-connected. David G Lewis ...!bellcore!nvuxr!deej (@ Bellcore Navesink Research & Engineering Center) "If this is paradise, I wish I had a lawnmower."