Xref: utzoo sci.electronics:3096 sci.astro:2225 comp.dcom.modems:1977 comp.misc:2581 rec.ham-radio:5076 Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!mailrus!ames!necntc!frog!die From: die@frog.UUCP (Dave Emery) Newsgroups: sci.electronics,sci.astro,comp.dcom.modems,comp.misc,rec.ham-radio Subject: Re: N.B.S. Time Service Summary: Some calls are specially routed Keywords: Time Ticks Message-ID: <1120@X.UUCP> Date: 8 Jun 88 09:00:00 GMT References: <455@trane.UUCP> <4691@watcgl.waterloo.edu> <585@otto.COM> <317@ncar.ucar.edu> <587@otto.COM> Reply-To: die@frog.UUCP (David I. Emery) Organization: Charles River Data Systems, Framingham MA Lines: 43 In article <587@otto.COM> glenn@otto.UUCP (Glenn Scott) writes: > > Nevertheless, my point was that the receiver does not direct the routing. >If I make a call, it is routed via the most viable route. Satellite delays >notwithstanding. > >Glenn It is my understanding that the modern 4ESS/CCIS/SS7 AT&T long distance switches (and probably other carriers as well) can and do under at least some conditions selectively route calls to particular destinations over particular types of media (such as fiber rather than satellite). This capability was incorperated in the telephone network some years back in an effort to reduce the number of sensitive conversations that are routed via certain microwave and satellite links that the Russians and other foreign intelligence services routinely monitor. As I understand it the network is capable of refusing to route calls to particular specific destinations via less secure paths if all the more secure ones are busy. Further the detailed billing tapes available from your telephone carrier contain information about how a specific call was routed and perhaps whether it was specially routed or not. I do not know whether the software involved can specially process certain blocks of numbers within an office code differently than the rest of the office code but I suppose this is quite possible. Whether the knowlage of what numbers to process specially is contained in a database at the originating toll center or whether the destination serving toll office can pass back a CCIS message identifying a number as requiring special handling I do not know. It is therefore quite reasonable to suppose that when the NBS time number is called it is specially recognized and the call routed via terrestrial rather than celestial paths at least over AT&T. -- ---- David I. Emery Charles River Data Systems 983 Concord St. Framingham, MA 01701 Tel: (617) 626-1102 uucp: ...!decvax!frog!die