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

[hkirrc.patrick]

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
>
>
>
>
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