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The Telecom Digest for September 8, 2011
Volume 30 : Issue 224 : "text" Format
Messages in this Issue:
Re: Does SMS messaging keep going when cellular voice is down?(Ken)
Re: Does SMS messaging keep going when cellular voice is down?(Michael D. Sullivan)
Re: Does SMS messaging keep going when cellular voice is down?(John C. Fowler)
Re: Does SMS messaging keep going when cellular voice is down?(danny burstein)
Cell phone service and disasters article(HAncock4)

====== 30 years of TELECOM Digest -- Founded August 21, 1981 ======

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Date: Wed, 07 Sep 2011 07:11:17 -0600
From: Ken <ken@globalengineeringmgmt.com>
To: telecomdigestmoderator.remove-this@and-this-too.telecom-digest.org.
Subject: Re: Does SMS messaging keep going when cellular voice is down?    
Message-ID: <4E676D75.1070904@globalengineeringmgmt.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" <mds@camsul.com>
To: telecomdigestmoderator.remove-this@and-this-too.telecom-digest.org.
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 <j46amj$q03$1@dont-email.me>, 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" <johnfpublic@yahoo.com>
To: telecomdigestmoderator.remove-this@and-this-too.telecom-digest.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: <j46amj$q03$1@dont-email.me>

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, johnfpublic@yahoo.com




Date: Wed, 7 Sep 2011 03:56:34 +0000 (UTC)
From: danny burstein <dannyb@panix.com>
To: telecomdigestmoderator.remove-this@and-this-too.telecom-digest.org.
Subject: Re: Does SMS messaging keep going when cellular voice is down?   
Message-ID: <j46q1i$565$1@reader1.panix.com>

In <j46amj$q03$1@dont-email.me> 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
		     dannyb@panix.com 
[to foil spammers, my address has been double rot-13 encoded]




Date: Wed, 7 Sep 2011 10:29:44 -0700 (PDT)
From: HAncock4 <withheld@invalid.telecom-digest.org>
To: telecomdigestmoderator.remove-this@and-this-too.telecom-digest.org.
Subject: Cell phone service and disasters article  
Message-ID: <68bf754e-63f2-4ded-a5cc-915beae57444@v18g2000yqj.googlegroups.com>

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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