Replacing PSTN with VoIP wise? Was Re: Phone networks struggle in Hurricane Katrina's wake

Thu Sep 1 16:41:40 UTC 2005

Michael.Dillon at btradianz.com wrote:
>>But then, people don't really care about this, as cell is in the 
>>exact same boat and huge numbers of people rely on just their cell 
>>phone and no longer have a fixed line (in Europe at least).
> 
> 
> I have read accounts that suggest that cellphone subscribers
> from New Orleans only have one way service. In other words,
> if you left New Orleans with your cellphone then you can
> make outgoing calls but no-one can call you. I don't know
> how widespread this is, but knowing that there has to 
> be an SS7 switch in New Orleans directing those incoming
> calls to your new location, I can imaging that loss of
> such a switch would create problems.

It is sometimes the case in disasters that people from inside can call 
out but that people from outside can't call in because the circuits into 
the disaster area become overloaded.  This would hold true especially in 
  the case where many people in the disaster area have no access to 
working phones, so those with working phones can easily get a free 
outbound circuit - meanwhile frantic friends and family clog up the 
incoming circuits trying to reach phones that are out of service or 
people who simply aren't near the phone and who can't answer but those 
calls still tie up circuits each time they are attempted.

I've had several reports that cell phone users who can't make *or* 
receive calls are successfully sending *and* receiving SMS.  It could be 
that the problem is one of not enough cell channels and working phone 
circuits for all the phone calls people want to make, but that the SMS 
channel is not overloaded and thus SMS traffic can zip on thru (when the 
cell has power and can reach a working cell tower).

jc