Verizon PSTN continued

Sean Donelan sean at
Thu Nov 9 20:22:56 UTC 2006

On Tue, 7 Nov 2006, Chris L. Morrow wrote:
>> Working with 2 other carriers on a similar issue, response I rec'd was
>> congestion due to automated political dialers. Not sure if I believe
>> that or not...
> you'd think they'd have systems monitoring that and trimming down the
> 'fat'? or can they do that? (legally I mean, sorta like QOS for the phone
> network I suppose)

They can, and do.  But SS7 interconnect battles between carriers are about 
as much fun as peering battles between ISPs, lots of finger pointing and 
blustering and more lawyers. If you lose SS7 links between carriers, and 
there is not enough SS7 capacity remaining, the SS7 systems start 
"flapping" (the SS7 folks probably use a different term, but it gives the 
IP folks some idea of what happens).  It has happened a few times.  I 
expect the SS7 vendors and protocol wizards are thinking up more clever 
ways to address it.

It has nothing (essentially) to do with the type of calls being made, 
although high call volumes always make any problem worse.  Another time
it happened was just before Christmas a few years ago, during peak 
shopping time and the dialup credit card authorization numbers (and lots 
of other types of numbers) got jammed up during a SS7 incident as I found 
out doing my Christmas shopping that afternoon.

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