From memory (I haven't lived in the UK for 11 years) the electrical characteristics are pretty much the same: -48V, 35mA loop current, 600ohm complex impedance. One key difference is an extension needs to ring, but a DDI line does not. The different cards you see used may be because the DDI port has no ringer, or it may be a marketecture issue - they can probably squeeze more money out of the customers for the DDI ports. If they get full approvals only on the DDI card, then only a pricy DDI card can be used to attach to the DDI lines.
Regards, Steve
hkirrc.patrick wrote:
Hello Steve,
You are exactly right about the DDI line and thank you for clearing up the 600 ohm loop.
Can you tell me other electrical details? It's just that all the PBXes (that I know) uses
different cards for DDI lines and analog extension lines and since the CO normally or at
least, expected to be much further away than an extension phone, I was wondering if there's
a difference in the electrical requirment.
thanks again, patrick
Steve Underwood wrote:
Hi Patrick,
You are in the UK, right (at least DDI strongly suggests that)? This is the commonest signalling for a DDI line on an analogue pair. The line is behaving just like the main exchange is a telephone. It picks up the line, by applying a 600ohm loop, and dials (with pulses per second or DTMF) into your PBX. Your PBX port is behaving like it is a public exchange, with a phone attached.
Electrically, Digium's FXS card should do the job you need, but others will have to tell you whether * has the software features needed to make this work (it should certainly be pretty close).
Regards, Steve
hkirrc.patrick wrote:
as my first project with *, i would like to replace our old neax2400(sds) with an * server.
i've got an X100p and a TDM400 on hand already.
for the CO lines, the X100p works ok with fxsks signaling though there are still strange
things happening every now and again but more testing is on the way.
my real big problem is the DID lines which our telcos call DDI lines; (incoming calls only) i disconnected a running DID line from our PBX and did a bunch of tests on it and found the following:
* line from telco has NO voltage
* the port from pbx is supplying the power(voltage) but no dial tone
*the moment i disconnected the DID line from the PBX port, an alarm is triggered at the telco CO
* i can attach an ordinary analog phone to the PBX PORT, pick up the handset and
send (dial) 4 dtmf digits (being the last 4 digits of our DID number),
the PBX will bridge me to the appropriate extension phone.
* if or when the extension phone picks up, the PBX reverses the polarity on the line
what type of signaling should i be using for such a line?
many thanks in advance, patrick
_______________________________________________ Asterisk-Users mailing list [EMAIL PROTECTED] http://lists.digium.com/mailman/listinfo/asterisk-users
