Re: (ASCEND) Huntgroup rollover on Max

[Peter Galbavy <Peter.Galbavy@knowledge.com>]

On Thu, Nov 11, 1999 at 01:25:31PM +0100, Blaz Zupan wrote:
> We have a Max 6000 evaluation unit and I'm wondering about the following.
> The 6000 supports 4 E1's (we're in Europe), so this is 120 channels. But
> it only supports a maximum of 96 analog modems. Now let's say we have 8
> E1's in a huntgroup, 4 on the first Max and 4 on a second Max. Let's say
> that all 96 analog modems on the first max are occupied and the 97th call
> comes in. Will it correctly hunt to the second Max, which will be able to
> accept it, because it has analog modems available? I was told by the
> company that gave me the evaluation unit that this is possible, but I have
> the feeling they are just trying to sell me the box and would even tell 
> me that I can slice and dice with it :-)

Yep, they are.

Depending on the signalling type - I am assuming Q.931 - is it not
possible with current telco equipment to retry the presentation of a
call. Let's look at what happens:

	MAX 1:	Accept call 95
	MAX 1:  Accept call 96
	MAX 1:  Reject call 97	----> teclo (say DMS100) would return busy

This kind of thing is possible with other singalling systems, such as
DPNSS / DASS2 in the UK, but most telco's will not support this.

My understanding is that Q.931 has timing issues which make it
effectively impossible to carry the call around equipment until it is
answered, without holding it in a IN network type queueing system.
This is very resource intensive.

It is effectively "call forward on busy".

> I'm asking because this is simply not possible on PM3's. If the above
> scenario would happen on a PM3, the user would get a busy. The only way to
> fix this would be to have forward on busy, but then we'd have to pay for
> the forwarded calls.

Yep. Got it in one.

There are various hacks that you can do to make this work, but I would
recommend using just 3 PRI's and 96 modems - keeping the 6 as hot
spares that are rotated through the pool. This also solves a few
probelsm when things get busy in terms of modem reset times etc.

Regards,
-- 
Peter Galbavy
Knowledge Matters Ltd
http://www.knowledge.com/
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