[Asterisk-Dev] Experienced Sysadmin/Programmer having major trouble with British Telecom Caller ID & Distinctive Ring

[Cats Muvva]

Dear All,

I've just joined this list in the hope that one of you could help me. I'm
secretary of a charity so we don't have much money to spend on support or
equipment - anyway Asterisk appears to meet our requirements more than
adequately.

I'm trying get both Caller ID and distinctive ring detection running on a BT
line without any luck at all. For the time being, I've abandoned trying to
detect distinctive ring and am concentrating on getting CID working, 'cos
right now, it ain't.

I'm using the latest CVS head Zaptel and Asterisk with a Digium TDM400. I've
got zaptel configured correctly - at least it doesn't throw out any error
messages.

My zapata.conf is: ==============

[channels]
language=en


context=incoming
signalling=fxs_ks
cidsignalling=v23
cidstart=polarity
usecallerid=yes
channel => 4

group=2
context=internal
signalling=fxo_ks
channel => 1
channel => 2

========================


The log file contains this when I ring from my mobile telephone: ===========
Aug 24 10:35:12 VERBOSE[27670] logger.c: Asterisk Ready.
  == Starting post polarity CID detection on channel 4
Aug 24 10:35:12 VERBOSE[27670] logger.c:     -- Starting simple switch on
'Zap/4-1'
Aug 24 10:35:15 NOTICE[27670] chan_zap.c: Got event 17 (Polarity
Reversal)...
Aug 24 10:35:15 DEBUG[27670] chan_zap.c: Exception on 16, channel 4
Aug 24 10:35:15 DEBUG[27670] chan_zap.c: Got event Ring/Answered(2) on
channel 4 (index 0)
Aug 24 10:35:15 DEBUG[27670] chan_zap.c: Setting IDLE polarity due to ring.
Old polarity was 1
Aug 24 10:35:15 VERBOSE[27670] logger.c:     -- Executing NoOp("Zap/4-1",
"") in new stack


================
NB. The mobile network does pass CID - my house telephone, connected to this
exchange line, shows the calling number.

This is not always consistent. Sometimes raher than the polarity reversal I
get an Event 2 (Ring/Answer). However, there is always one event or another
whilst processing CID. Either way, looking at the code, I see that getting
any kind of event whilst looking for CID on the line, will always
prematurely halt CID processing. I was reading BT SIN 227
(http://www1.btwebworld.com/sinet/227v3p4.pdf) that mentions a kind of
hand-shaking. There is a time-line for this on pages 9 and 30 of this
document. There is some indication in this document, though this isn't 100%
clear to me, that if an ancknowledgement tone is not sent, the exchange will
not send CID. For the life of me, I cannot see anything that appears to be
such an acknowledgement in the asterisk source code. However, BT's CID
thingy is based on Bellcore CLASS signalling, so perhaps the support is
there already in Asterisk.

I'm an OK sort of programmer (not a born hacker, tho'), but don't really
understand POTS lines (ISDN is another matter - I used to teach the
subject): so I'm be OK following a reasonably technical discussion.

I'd be very grateful to anyone for any light they could shed on what's
happening here.

Nicole King
Secretary, Inner Enigma
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