33 Years of the Digest ... founded August 21, 1981
Copyright © 2015 E. William Horne. All Rights Reserved.

The Telecom Digest for Mar 20, 2015
Volume 34 : Issue 55 : "text" Format
Messages in this Issue:
Re: Can't trace Blocked CID? (dold)
Re: cell Network time no longer provided (John Levine)
Re: Cell Network time no longer provided (Garrett Wollman)
Re: Cell Network time no longer provided (dold)

It is time to heal America. And so we must say to every American: Look beyond the stereotypes that blind us. We need each other. All of us, we need each other. We don't have a person to waste. And yet for too long politicians have told the most of us that are doing all right that what's really wrong with America is the rest of us. Them. Them, the minorities. Them, the liberals. Them, the poor. Them, the homeless. Them, the people with disabilities. Them, the gays. We've gotten to where we've nearly "them"ed ourselves to death. Them and them and them. But this is America. There is no them; there's only us. One nation, under God, indivisible, with liberty, and justice, for all.
William Jefferson Clinton

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Date: Fri, 20 Mar 2015 00:38:11 +0000 (UTC) From: dold@98.usenet.us.com To: telecomdigestsubmissions.remove-this@and-this-too.telecom-digest.org. Subject: Re: Can't trace Blocked CID? Message-ID: <mefq5j$54b$1@blue-new.rahul.net> dold@98.usenet.us.com wrote: > ***** Moderator's Note ***** > SS7 packets always contain the calling party ID, but the DISPLAY of > ... > Most LECs keep usage records of all calls, for use in trunk planning, That's what I recall. I was surprised to see that field populated after all the "couldn't trace" comments I've seen in the news, and our own experience with lack of followup back at the time I was at that telco. The only thing I could surmise was that it was a field that was dropped when records were saved to longer term storage, unless it was needed for billing that call. <-- Wild guess. Why isn't it used? This bomb threat was hollow. Would it magically have been traceable if there were a bomb? - - Clarence A Dold - Santa Rosa, CA, USA GPS: 38.47,-122.65 ***** Moderator's Note ***** SS7 is a separate system than AMA: the AMA records are used for billing, and SS7 for signalling routing orders to other CO's or tandems. AMA records are sent from CO's to billing centers, whereas SS7 datagrams are routed to other CO's or tandoms in the path of the call. Bill Horne Moderator
Date: 19 Mar 2015 02:41:48 -0000 From: "John Levine" <johnl@iecc.com> To: telecomdigestsubmissions.remove-this@and-this-too.telecom-digest.org. Subject: Re: cell Network time no longer provided Message-ID: <20150319024148.35134.qmail@ary.lan> >when LTE-only devices start to appear. But any LTE-capable device >could easily synchronize to an NTP server on the internet if the OS >includes that capability. So far as I know neither iOS nor Android >currently does, though you can get third party apps to add automatic >NTP synchronization to a rooted Android device. My wifi-only Nexus 5 Android tablet syncs its time automatically, so it's pretty clear that it's doing NTP. R's, John
Date: Wed, 18 Mar 2015 17:28:46 +0000 (UTC) From: wollman@bimajority.org (Garrett Wollman) To: telecomdigestsubmissions.remove-this@and-this-too.telecom-digest.org. Subject: Re: Cell Network time no longer provided Message-ID: <meccke$13u1$1@grapevine.csail.mit.edu> In article <CAMdng5uWe74+p7+FwwzXJM7KrLBEoA7GRZQME7-tUBQ-E4LhUQ@mail.gmail.com>, Shirley Márquez Dúlcey <mark.remove-this@and-this-too.buttery.org> wrote: >CDMA networks (Verizon, Sprint, and their MVNOs) are unlikely to make >that change because they MUST have accurate time sources available at >every cell site. Correct operation of the network requires that the >sites be synchronized within milliseconds, because CDMA does soft >handoffs as you travel. Microseconds, actually. The spec says 15 microseconds, if I recall correctly. >The network can reassemble partial reception from more than one site >to piece together your conversation, and that requires that the >timing be accurate. It's done by having a GPS time reference at each >site. Since accurate time must be available in any case, they might >as well continue to provide it to customers. They can't turn it off -- distribution of UT_{gps} is a mandatory part of the IS-95/IS-2000 protocol, and is available to anyone with a CDMA radio. There are timebases that are directly synchronized to CDMA (I have one) as an alternative to GPS that works in buildings where a GPS antenna is impractical. These will all break when the IS-2000 network is eventually shut down. -GAWollman --
Garrett A. Wollman
Opinions not shared by
my employers.
What intellectual phenomenon can be older, or more oft
repeated, than the story of a large research program
that impaled itself upon a false central assumption
accepted by all practitioners? - S.J. Gould, 1993
Date: Fri, 20 Mar 2015 00:41:50 +0000 (UTC) From: dold@98.usenet.us.com To: telecomdigestsubmissions.remove-this@and-this-too.telecom-digest.org. Subject: Re: Cell Network time no longer provided Message-ID: <mefqce$54b$2@blue-new.rahul.net> Kent Borg <kentborg.remove-this@and-this-too.borg.org> wrote: > several seconds as we entered the territory of some podunk wireless Around 2000, our entire company's Nextel phones had time that was off by quite a bit. One of the employees travelled to LA and back, and her time was correct, different from ours, until the next Daylight Savings transition, when it seems someone was more careful about setting the local time, and we all had a good time ;-) - - Clarence A Dold - Santa Rosa, CA, USA GPS: 38.47,-122.65 ***** Moderator's Note ***** When I was a Systems Analyst at NYNEX, we would occasionally have to write special one-time programs to correct AMA (Automatic Message Accounting) tapes when the clock was misset in the central office where the tapes had been recorded. The central offices did not have synchronization for their clocks, so each CO's time was set locally. I assume that this has changed: the AMA tapes were replaced by data lines, in order to be able to bill calls more quickly, but that also meant that there is no grace period between calls and billing, and thus no chance to do a "reality check" on incoming tapes. Bill Horne Moderator

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