RE: BT CD50 caller id -> computer conversion

["Kevin Hawkins" <lists@xxxxxxx>]

            The
original hack works on the basis that at some point the
incoming CID data (which is like a modem tone) is demodulated and appears
as
a serial data stream at TTL levels. This is then fed from one part of
the
circuitry to another and can be 'picked up' and translated to RS232 and
optically isolated from the telephone line. What comes out is a long
string
of data that is not error checked and contains a lot of padding. Your
software needs to strip this padding and then extract the required
information. This is fairly easy to do. The stream is fully documented
in
the BT spec document.

            As to
these cheaper CallerID units - if you can find this same
point that links the parts of the circuitry (a TTL serial data stream)
then
it should work - If the modem part is separate from the processor on
the
unit this is quite likely to be possible but as with all these things
the
cost perhaps reflects that they have reduced the chip count way down and
it
may all be one chip. Gonna need to take one to bits and see what's
inside
and get a scope out.



           
Kevin



-----Original Message-----
From: James,Daniel [mailto:Daniel.James@xxxxxxx] 
Sent: 24 January 2003 12:40
To: 'ukha_d@xxxxxxx'
Subject: RE: [ukha_d] BT CD50 caller id -> computer conversion



Hi Jon

This is really interesting, thanks for posting it up..

I see that Telephones online have Caller display units for under a fiver
for
2,

http://www.telephonesonline.co.uk/details.asp?prodID=356
<http://www.telephonesonline.co.uk/details.asp?prodID=356&title=Caller+Displ
a> &title=Caller+Displa
y+Phones

Do you know if other BT CD boxes have the same chips as the CD50?

Regards

Daniel

-----Original Message-----
From: Jon Payne [mailto:jgpayne@xxxxxxx]
Sent: 24 January 2003 12:25
To: ukha_d@xxxxxxx
Subject: [ukha_d] BT CD50 caller id -> computer conversion


Some time ago someone asked me about how to convert a CD50 caller id box
to
provide RS232 output, to my shame I completely forgot to make the web
page
available. I found it whilst routing through my projects folder so I've
updated it a little bit and copied to my web server - it can be found
here:
http://www.photon.dyndns.org/electronics/btcd50conversion/index.html
(this
on on the end of my ADSL line so it may be a bit slow).

I'll try and get some xPL or xAP s/w together soon... probably on the
TINI
(although it'll work on the PC too hopefully).

Cheers,
Jon

[Non-text portions of this message have been removed]


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