Re: ISDN - was:(PM) 2 PM3's, not fully populated.

David Giller (dave@pdx.net)
Fri, 13 Feb 1998 18:12:49 -0800

MegaZone wrote:
> >As I understand it, there is no way to tell the switch to generate a busy
> >signal for the user if there are no modems available. Instead, it just
>
> RIght.
>
> >hangs there in dead air. Can't a busy signal at least be simulated by the
> >PM3 on the channel even if it doesn't forward it to the next PM3? This way,
>
> Nope. You need a DSP to generate the busy, and the reason you want to
> generate a busy is you don't have any DSPs left. Yossarian would
> be proud.

OK, how about PRI. We are in the fortunate position of having more ISDN
customers than 56k dial-up. When I need more B-channels than my 2T can
give me, and I add another, what do I do? If I fully populate the first
box with modems, and the first 46 lines are used up, customers will get
busy signals, even though I have potentially thousands of $$ worth of modems
idle, and plenty of B-channels left to handle the calls.

I believe I understand that when you run out of modems in a PRI box, it
returns a busy signal as an ISDN cause code. Does this mean that if I have
two PM3s, and one is not populated (or underpopulated), I should make the
fully-populated box at the END of the chain of busy-forwarded PRIs? That
makes sense to me, but will the PM-generated ISDN busy signal trigger the
busy-forward? (and I suppose I have to be careful of per-call busy-forward
fees, as I am in GTE territory).

This wasn't a problem with 2e's, BRIs and analog modems, but then, we
didn't get 56k and then we had idle ISDN lines half the day and idle
modem lines the other half.

Thanks.

--
David Giller - (mailto:dave@pdx.net) - (http://pdx.net)
    Graydog Internet, Inc. - Portland Internetworks
       Wide Area Networking - Internet - Intranet
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