[asterisk-users] Detecting answer with ISDN (fork of Detecting answer with an analogue card)

[Andrew Kohlsmith]

On Monday 05 February 2007 5:50 pm, Stefano Corsi wrote:
> Ok, understood. But I'm still very curious: what is the wife test ?! :)

It doesn't matter how many bells and whistles it has, it won't stay if it 
can't let her place a simple, straightforward phone call and act just like 
any other normal phone.

If you can make it do that, you can add damned near anything you want to it 
and the only reproach you'll get is the odd eye-roll and "ok, dear."  :-)

> Because my customer bought a custom server with only _two_ PCI full
> length slot and those are used for the two TDM2400 cards (40 fxs). I
> wasn't aware of this "ANSWER detection" problem and my solution is
> aimed to an hotel, so the billing is, how to say, mandatory... Then I
> have to pay some piece of hardware that _does_ detect answer and that
> does not request any PCI slot... the cheaper I've found (and with
> good reviews) is the Inalp Patton. Could you help me understanding
> if, with an ISDN device connected to asterisk with SIP, I could be
> reasonably sure to get correct CDR billing records? And what about
> the case that Andrew pointed out: the "the number you have reached
> has been disconnected" case... would I get a billing record or not,
> using an ISDN device connected to Asterisk with SIP ?! The telco does
> not bill for those answers, so the hotel's guests probably expect
> themselves not to be billed too...

If this is for FXS, you don't have to worry about it.  The only states you 
have to worry about are whether they're on the phone or not.  If they are, 
it's busy (and you can use call waiting, which will still give you valid 
CDR), if they're not, it's ringing.  If they never pick up, it's fine, 
that'll get a NOANSWER.  FXS isn't a problem since Asterisk is ringing the 
lines.  It's FXO that's the problem; you place a call and the remote switch 
that's actually doing the connecting has no way to tell you whether the other 
end actually picked up or not.

The only thing you have to worry about is the far end, and if you use BRI or 
PRI there (or SIP) you're golden.

> PBXs in Italy seems to react to the Telco "scatti" ("marks", "billing
> pulses"). Isn't there such a concept in US? Is there a way to
> intercept such Telco events?

I'm not aware of any, no... but let's hope that Eric or one of the Steves 
pipes up...  :-)

-A.