asterisk users - Jan 2007 - Detecting Disconnected Numbers - PRI

I am trying to automatically detect disconnected numbers when using the
outbound dialer I have written.

* Some numbers hang up immediately with a Cause Code > 0 and no voice
treatment
* Some numbers get voice treatment with a PROGRESS indication and an
associated Cause Code > 0
* Some numbers get voice treatment with a PROGRESS indication and no
associated cause code (CC=0)

My application can pick up the PROGRESS indication (if I get one) and handle
the hangup, but not if I don't get a cause code!

Is there anything I can do to ensure that I always get a PROGRESS indication
with cause code or a hangup with cause code?
Behaviour of the PRI seems to differ across telcos and also across numbers.

I don't want to just assume hangup on PROGRESS indication as this may not be
a disconnected number - it might be a forwarded or redirected number.

I need to achieve consistency and this is proving very difficult.

Has anyone else had this issue and if so, which tree should I be barking up?

cheers,

Mark.


-- 
regards,

Mark P. Edwards
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<original message>
I am trying to automatically detect disconnected numbers when using the outbound
dialer I have written.
?
* Some numbers hang up immediately with a Cause Code > 0 and no voice
treatment
* Some numbers get voice treatment with a PROGRESS indication and an associated
Cause Code > 0
* Some numbers get voice treatment with a PROGRESS indication and no associated
cause code (CC=0)
?
My application can pick up the PROGRESS indication (if I get one) and handle the
hangup, but not if I don't get a cause code!
?
Is there anything I can do to ensure that I always get a PROGRESS indication
with cause code or a hangup with cause code?
Behaviour of the PRI seems to differ across telcos and also across numbers.
?
I don't want to just assume hangup on PROGRESS indication as this may not be
a disconnected number - it might be a forwarded or redirected number.
?
I need to achieve consistency and this is proving very difficult. 
?
Has anyone else had this issue and if so, which tree should I be barking up?
?
</original message>


Yep, I experienced this frequently.  I have several PRI vendors and they all
give me the same line of crap: "Well, PRI is good, but it's not
perfect..."  Sad but true.  I feel comfortable in saying that there is no
100% guaranteed way of detecting disconnected numbers on a PRI.  I've done
lots of testing and come to the conclusion that you have to do your best to work
around it.  For example, I know that phone number xxx-yyy-zzzz is disconnected. 
I dial it 25 times with Asterisk.  18 times I get one cause code (like
'invalid' or fast busy - I don't recall the exact cause code
number), 6 times I get PROGRESS indicating ring-no answer and 1 time I get
traditional busy.  All calls to same phone number, same provider, made one right
after the other.  Oddly enough, if I call the number on a POTS line I *ALWAYS*
get the disconnect message.  It's one case where advanced technology yields
poorer results than the old stuff.

I know that doesn't help but I wanted you to know that you're not alone.

-MC