asterisk users - Jul 2006 - billed calls when cellullar phone is unreachable

We have a customer routing calls trough a pri (digium board), our system 
then terminates the calls in various places (let say we offer LCR).

When we route a call to an unreachable cellular phone we know it cause 
we get a particular ${HANGUPCAUSE} so we don't bill that call even if 
billsec is > 0 (the duration of the "cellular is unreachable bla
bla"
message),  but the customer says their system too records the call as > 
0 and their expected behaviour is to have the call recorded as duration 
== 0.
(I'm supposing the customer is noticing the cellphones cause of the high 
traffic, but probably this happens also with other kind of "service 
messages" which aren't to be billed, have to try)

Now, is there some standard (we are in italy) which as to do with AMA 
codes / PRI_CAUSE / HANGUPCAUSE whatever that "non asterisk" systems 
expects to work right or have I to go trough "try everything comes to 
mind until it works" ?

for example setting some PRI_CAUSE on the channel based on the type of 
the HANGUPCAUSE I see ?

Why this seems to me a problem of the customer but I'm resolving it ?

that's roughly the extension :


exten => _X.,1,AGI(agi://127.0.0.1:54321/SomeAgiHere?someArgumentsHere)
exten =>
_X.,n,GotoIf($["${CALLABLE}"="TRUE"]?chkmax:hangup)
exten => _X.,n(chkmax),Set(GROUP()=${TECH_PRE})
exten => _X.,n,GotoIf($[${GROUP_COUNT(${TECH_PRE})} >= 
${MAX_CALLS}]?hangup:dial)
exten => _X.,n(dial),Dial(${STR_DIAL})
exten => _X.,n(hangup),Hangup

exten => h,1,Set(CDR(userfield)=${USERFIELD}-${HANGUPCAUSE})

> When we route a call to an unreachable cellular phone we know 
> it cause 
> we get a particular ${HANGUPCAUSE} so we don't bill that call even if 
> billsec is > 0 (the duration of the "cellular is unreachable bla
bla"
> message),  but the customer says their system too records the 
> call as > 
> 0 and their expected behaviour is to have the call recorded 
> as duration 
> == 0.
> (I'm supposing the customer is noticing the cellphones cause 
> of the high 
> traffic, but probably this happens also with other kind of "service 
> messages" which aren't to be billed, have to try)
I would expect these kind of messages to be played without 
"answering" the call. IIRC on ISDN this is done using a 
FACILITY message with a "start audio" IE included (I'm not 
that much into ISDN to be more precise).

On H.323 this is called "early media" and in SIP this would be 
signalled using a 186 Session Progress message.

-- 
Andreas Sikkema                       BBned NV
Software Engineer                Planeetbaan 4
+31 (0)23 7074342            2132 HZ Hoofddorp