30 Years of the Digest ... founded August 21, 1981
The Telecom Digest for September 8, 2011
====== 30 years of TELECOM Digest -- Founded August 21, 1981 ======
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Date: Wed, 07 Sep 2011 07:11:17 -0600 From: Ken <email@example.com> To: firstname.lastname@example.org. Subject: Re: Does SMS messaging keep going when cellular voice is down? Message-ID: <4E676D75.email@example.com> Bill Horne <bill@horneQRM.net> wrote: >I just read an email that claims cell phone text messaging (SMS) keeps >going when cellular voice service is down. Please tell me if this is >true or not. It depends on what you mean by down. The link between your phone and the tower is the same for voice and SMS, so if the tower is not operational due to an extended power loss or the backhaul link broken, then nothing works. What's more common is an emergency overload situation. When that happens, voice calls are blocked or restricted to responder priority only, but control messages to/from the phone which includes the ability to send and receive text messages remains available.
Date: Wed, 7 Sep 2011 11:00:12 -0400 From: "Michael D. Sullivan" <firstname.lastname@example.org> To: email@example.com. Subject: Re: Does SMS messaging keep going when cellular voice is down? Message-ID: <CA+K-LfZ9sBckKYOXsoMC6xGEUT_+tnx+t4DM2D_=p+LXZH88OQ@mail.gmail.com> In Message-ID <firstname.lastname@example.org>, Bill Horne asked: >I just read an email that claims cell phone text messaging (SMS) keeps >going when cellular voice service is down. Please tell me if this is >true or not. Yes and no. SMS keeps going when the cellular voice traffic is so heavy that the system seems like it is down. SMS uses the signaling or paging channels and does not require a dedicated connection, and moreover does not use much "bandwidth," so thousands of text messages occupy the same network capacity that would support only one voice call. But when the voice service is down because a tower is out of commission, there is no signaling channel and thus no SMS. -- Michael D. Sullivan Bethesda, MD
Date: Wed, 7 Sep 2011 07:45:09 -0700 (PDT) From: "John C. Fowler" <email@example.com> To: firstname.lastname@example.org. Subject: Re: Does SMS messaging keep going when cellular voice is down? Message-ID: <1315406709.10339.YahooMailClassic@web160310.mail.bf1.yahoo.com> Responding to: Message-ID: <email@example.com> On Tue, 06 Sep 2011 19:34:36 -0400 Bill Horne <bill@horneQRM.net> wrote: > I just read an email that claims cell phone text messaging (SMS) keeps > going when cellular voice service is down. Please tell me if this is > true or not. It depends why the voice service is down. If the voice service is down because the only cell tower in range just got hit by a giant meteorite, then obviously, your SMS isn't going to work, either. If you can't get through by voice because some big event is happening and everyone is trying to call everyone at once, overloading the system, then SMS could very well get through when voice does not. SMS is carried at the signalling level and uses much less bandwidth than voice, so it's easy to prioritize. If "voice service is down" means "calls start OK but keep getting dropped quickly", then it's very likely SMS will make it through. John C. Fowler, firstname.lastname@example.org
Date: Wed, 7 Sep 2011 03:56:34 +0000 (UTC) From: danny burstein <email@example.com> To: firstname.lastname@example.org. Subject: Re: Does SMS messaging keep going when cellular voice is down? Message-ID: <email@example.com> In <firstname.lastname@example.org> Bill Horne <bill@horneQRM.net> writes: >I just read an email that claims cell phone text messaging (SMS) keeps >going when cellular voice service is down. Please tell me if this is >true or not. >TIA. There's a big "it depends". If the entire cell network (towers, backhaul, etc.) is "down" for fifty miles around you, you ain't getting through. If it's up but the voice channels are all in use, then yes, the SMS should get through. If the towers near you are down but the one 9 miles away is working, then it's quite possible you won't be able to get a voice line through it. But since SMS is "stored", so to speak, it can stay "on your handset" for fifteen minutes (number for illustration) until you walk on the other side of the road and get a short-in-time workable link to the tower. (And vice versa for someone sending you something). -- _____________________________________________________ Knowledge may be power, but communications is the key email@example.com [to foil spammers, my address has been double rot-13 encoded]
Date: Wed, 7 Sep 2011 10:29:44 -0700 (PDT) From: HAncock4 <firstname.lastname@example.org> To: email@example.com. Subject: Cell phone service and disasters article Message-ID: <firstname.lastname@example.org> An article on CBS News explores if we can count on cell phone networks in disasters. excerpts: "Since 9/11, wireless networks have been tested time and again, and their performance has been shaky. A major blackout in the Northeast in 2003, Hurricane Katrina in 2005, and the Minneapolis bridge collapse in 2007 put strains on local networks. Cellular service in New York City even ground to a halt last month because of a minor earthquake centered several hundred miles away. Undoubtedly, with each crisis, operators have learned more about what they can do to keep service up and running. But there's a flip side to that growing expertise: we're more dependent than ever on cell phones." . . . "The biggest problem wireless networks face today in a crisis is a rapid increase in usage. The networks don't have enough capacity to handle the surge in call volume. Cellular networks are designed to handle a certain amount of calls in each cell site or region, with wireless operators carefully calculating how much usage is needed to serve the average usage volume while having just enough capacity to handle spikes in demand. The problem occurs when a disaster hits, and thousands of people all at once pick up their phones to call someone, send a text message, update Twitter, and so on. There simply isn't enough capacity in the network to allow everyone in a cell site to make a phone call at the same time." . . . "An analyst said most networks are designed to handle only about 20 percent to 40 percent of maximum traffic, with 40 percent being on the conservative side. 'It's just economic insanity for any carrier to try to solve the congestion problem,' " . . . for full article please see: http://www.cbsnews.com/stories/2011/09/07/national/main20102546.shtml?tag=stack
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