Re: Re: How to get Caller ID into a PC from an ntl line...?

[Kevin Hawkins <lists@xxxxxxxxxxxxxxxxx>]

Patrick Lidstone wrote:

>>Also interested if the multiple units interfere with each other at
>>
>>
>all .
>
>
>>This can happen with the 'message waiting/1571' capable units which
I
>>think are the ones on eBay as each one takes the line 'offhook' for
a
>>brief period after any call to listen for interrupted dialtone
which
>>indicates messages waiting. If two+ units do this automatically
then
>>
>>
>the
>
>
>>line constantly goes on/off hook as each triggers the other.
>>
>>
>
>Are you sure?
>
Yes.. at least that's they way my current units work...

>It isn't technically necessary to go off-hook to detect
>message waiting as there is a message waiting facility message as part
>of the SIN which can be sent by the exchange independently of any
>incoming call (ie no need for the phone to actually ring). Whether
>this is supported by BT in real life, I don't know.
>
>
Ahh yes... I saw that and I have eagerly inspected incoming SIN packets
when I know I have messages waiting. The SIN spec even says it will tell
you how many calls are waiting, But from my exchange that parameter just
never carries any valid data :-(.  It would have been really nice to get
at it xAP wise otherwise. On some exchanges maybe it's implemented.

I hadn't realised BT sent a SIN packet without a ring when a message was
left on 1571.  Maybe this is sent just as a line reversal which is how
call waiting CID is sent and the Meteor ignores these anyway. It could
be that the internals of the Meteor (the limited processing) strip this
flag anyway but I did have a modded CD50 on the line for a while too.
Must try that again in case the data is now present.

I have one 'telecom 630' CID unit here that operates via the 'off hook /
interrupted dialtone' method - I see these off/onhook messages from
Meteor after every call , and in fact I had to block them in xAPTel.  I
bought one of the eBay £2 CID units and the two interacted casing
continual ONOFF hook transitions , so I'm fairly sure the BT branded
eBay ones work like this.      Interestingly my 630 unit has a switch
you enable if there are other 'message waiting' devices connected to
stop this happening but the eBay units don't. Regardless it didnt solve
my problem and as my 630 unit has CID call history I stayed with just
that.   It may be that the newer eBay units are self tolerant (as they
dont have this switch) and presumably could be well synchronised to
ignore each other...  hence the Q to Andrew......

K