[Asterisk-Users] Scalable IVR

[Gregory Junker]

Back in 95-97 when I worked with Federated Department Stores' Customer
Call Center IVR, it was implemented using IBM DirectTalk on RS/6000's.
(Federated is the parent company of Macy's, Lazarus, Bloomingdales, etc,
so it's not a small company).

Each RS/6000 had 4 voicepaks (24 lines per, or a T1 per voicepak).
Depending on which time of the year it was (obviously, for a retail
concern Christmas was peak season) we would have between 4 and 7 RS/6000's
running the various call center IVR systems. That means 4*96 = 384 to 7*96
= 672 concurrent lines possible. The system was set up such that lines
were not dedicated to a particular store (and that call load was balanced
across machines), and still there were times (rare) that busy signals
happened.

We had 17 T3's (17 * 24 * 28 = 11,424) voice lines coming into this one
facility at the time. The IVR would do an ISDN transfer to live call
agents when applicable, so the actual call load at any given time could be
around 1,500-2,500 simultaneous (both IVR and agent), even during peak
season.

Before I left, FDS opened up two more regional call centers in Tempe, AZ
and Tampa, FL, to take the load off the main center. These were set up
similar to the main one, with fewer T3s inbound. So peak call volume could
typically reach, MAYBE, 5,000-6,000 (both IVR and live agent) during
insane times, during peak season, across three call centers separated by
about 2,000 miles each.

I say all this because I SERIOUSLY doubt that Digvijay's IVR system will
ever need to approach 10,000 simultaneous calls. Even popular call-in
public polling doesn't see that sort of call volume, as I understand; the
PSTN infrastructure would have a job just handling 600,000 calls per hour
to a single PBX.

Anyway, the prohibitive cost is in the telecom, not the hardware, side of
the equation: Like Steve said, to support 10,000 simultaneous calls you
will need some serious incoming copper, and that monthly recurring cost,
even in India, will undoubtedly swamp the one-time cost of
hardware/software.

My $0.02
Greg

> On Fri, 2004-05-14 at 12:37, digvijay singh wrote:
>> Hi,
>> I am an asterisk newbie and looking around for information . I wish
>> someone  could take their valuable time off to answer my query in
>> detail. I wish to set up an IVR system that can allow user
>> authentication and  therefter accept 2-3 inputs from users ..generate
>> a key and transmit the  same in voice back to the user .
>> The system will intially have small load but if  the whole package in
>> future  may have huge loads .. from 1000 to 10000 simultaneous peak
>> time callers  with 1 minute duration calls ( just to mention how
>> scalable we would ideally  desire it to be )
>> At present we would need a maximum of 10 simultaneous users peak load
>> capability.
>> From what i know so far asterisk is the most cost effective and sound
>> option.
>> Now to my question..
>> 1-) What would be the hardware requirements in these different cases
>> a-) for a single analog phone line for demo purposes intially to
>
> Just about anything with a PCI bus, maybe even a P133 would cut this.
>
>> b-) a peak time 10 simultaneous calls facility and later
>
> 10 simultaneous callers needs to switch up to either T1, PRI, or E1
> depending on location, cost, and extra needed features.
>
>> c-) going upto 10,000 simultaneous calls scalability
>
> 10,000/30(E1) is 333.33 circuits. At a max of 4 circuits a board you are
> looking at 84 cards. With a max of 2 cards per machine, you are looking
> at 42 machines.
>
> My guess(and a bit uneducated in your needs) is that you will not have
> 10,000 people calling at the same time. My guess is you might get 10,000
> over the course of 1 hour which breaks down to a call initiation every
> 2.777 seconds, or 167 calls per minute. With this in mind, you only need
> 167*call duration + fudge factor number of lines. You quote of a 1
> minute call time would make you need 167 lines plus some fudge of about
> 10 or so lines. 177 lines is only 6 E1 circuits or 8 PRI circuits. Both
> of which could be handled by 2 TE4xxP cards on one or two machines.
>
> For that kind of call load, your interaction application should be
> written in C and made a module of asterisk to eliminate startup costs.
>
>> 2-) Where can i procure the hardware from
>
> Digium, or one of the resellers listed on their site.
>
>> I was thinking of taking  30 access channels of 64 Kbps and 1
>> signalling  channel of 64 Kbps (30B + D). for an ISDN compatible EPABX
>> Kindly let me know of your opinion
>> Thanks
>> digvijay
>
>
> --
> Steven Critchfield  <critch at basesys.com>
>
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