Re: (PM) hunt group rollover when all modems are busy
Miquel van Smoorenburg (list-portmaster-users@news.cistron.nl)
7 Nov 1997 16:14:05 +0100
In article <3.0.3.32.19971107153423.03930aa0@pop3.a1plus.at>,
Michael Haberler <mah@austria.eu.net> wrote:
>The PM3 sends a busy signal to the ISDN switch when all analog modems are
>connected, and the next analog call comes in. The CW is that the telco
>switch now should rollover the call to the next PRI.
>
>I just had a long conversation with our Austrian PTT folks here on how the
>switches they use (Nortel, Siemens) handle the sitution. The answer is short:
>
>There seems to be no obvious way (for them..) to redirect a call to the
>next PRI in a hunt group if a PRI isnt fully busy but all modems 'behind'
>it are.
>
>This is the problem (*they* say):
>
>If a call reaches *the telco switch*, the switch *first* negotiates a
>B-channel with the PM3 to allocate. If the PRI is full, fine - switch rolls
>over to next PRI in hunt group since allocation fails, no problem here.
>
>If the PRI is *not full*, the B-channel allocation succeeds. Only *after
>the allocation*, the call setup message is presented on the D-Channel, with
>the bearer capability (voice or 64k). And only now the Pm3 can tell wether
>she can handle it (depending on all modems busy or not). Our PTT folk says
>if the get a reject at this point that was it for the call - there's no way
>to rollover to the next PRI - they say after b-channel allocation the call
>is 'committed' to this PRI (in transactional speak). Not good.
>
Aha - so that's the reason for that. I've talked to at least 10 different PTT
folks here in Holland but only about one third understood my question and
no-one came up with a satisfactory answer as to why they couldn't do it.
Another approach is to see if it is possible to get 2 different telephone
numbers, on the same set of lines. One group would roll from top to bottom
(ISDN) and the other from bottom to top (modems). Then just fully load
the first few portmasters with modems.
Ofcourse, the Dutch PTT also claims this is impossible without satisfactory
explanation (hopefully we'll have better luck with Enertel)...
Mike.
--
Miquel van | Cistron Internet Services -- Alphen aan den Rijn.
Smoorenburg, | mailto:info@cistron.nl http://www.cistron.nl/
miquels@cistron.nl | PTT's Het Net: Surfen in de gootsteen!
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