[asterisk-users] Asterisk concurrent calls count

[Mike Trest - On Travel]

At 11:44 AM 5/16/2008, you wrote:
>Yes, you could probably add 2 or 3 or 10 or 15 to the number of calls
>that a particular machine could handle, but from a support perspective, it
>doesn't matter how many the machine could theoretically handle, it matters
>how many it could handle in the particular installation in a supportable
>configuration (those are all those pesky variables we've been talking about).

Absolutely!   Right On!   Tell it like it is!    And many other 
cryptic encouragements.

With very large scale deployments, I have a set of numbers available 
in my head
that work well to predict how many machines will be needed for a 
particular application
but I wind up being surprised by non-predictable "rate of arrival"  issues.

Since most of my deployments are tied with Television and other promotional
support, a single reference by the on-screen (or on-radio) commentator, and the
phones are instantly flooded with thousands of new call setup 
requests.  Indeed,
one such incident in a NASCAR race with 13M viewers, produced 18,000 new calls
within two minutes.   The rate of arrival of new calls was dispersed 
to a farm of 60
Asterisk in three widely separated regions of the 
US.   However,  approximately
15,000 calls were actually dropped on the PSTN / SS7 network before 
ever reaching
three dispersed Asterisk farms.

Those farms were being "fed" inbound calls by a network of 
250+  Nortel switches with
millions of subscribers.   However, the Los Angeles area PSTN network 
access facility
had only 900 spare channels available in that two minute 
period.   Meanwhile, every asterisk
answered every call and joint the callers into appropriate conference 
groups until every
single available port was fully occupied.     This illustrates that 
such issues of call capacity
exist completely apart from the Asterisk or whatever machine is used 
for implementation.

So everyone should not be surprised by "it depends" kinds of answers 
to the question
of concurrent call counts.  This application was so far off the 
typical product specifications
that nothing published by Digium or anyone else could anticipate 
those surprises that
come when you least expect.

..mike..