Scooter
At 04:14 PM 11/7/97 +0100, Miquel van Smoorenburg wrote:
>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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