[Asterisk-Users] which TDM to use? DID line from telco with no dial tone and no voltage

[Steve Underwood]

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