[asterisk-users] Asterisk incoming caller id problem

[Gordon Henderson]

On Mon, 26 Mar 2007, Mike Jagdis wrote:

> On Mon, Mar 26, 2007 at 01:35:36PM +0100, Gordon Henderson wrote:
>> I've had issues with caller ID on TDM400 cards myself. I've never gotten
>> fully to the bottom of it either. Sometimes it works, and sometimes I get
>> nothing. (when a "normal" phone on the same line gets the ID OK all the
>> time)
>
> I got to the bottom of it - but I had to cheat and read chipset docs :-)

Fantastic!

> The ring detector's occasional misrecognition of polarity reversal
> as ring start is known and expected behaviour. The correct recognition
> strategy in the presence of polarity reversals is documented but
> wctdm doesn't implement it as standard.
>
> _Anyone_ using wctdm with a line that uses polarity reversals to signal
> pre-ring start of call will need the patch attached to bug id 9264.
> That's basically UK plus those countries that do DTMF CID after polarity
> reversal plus any random supplier that does gratuitous polarity reversal
> because they got a cheap switch and don't know much except "it seems
> to work with this config so we ain't touching it" :-).

Well I'll be stacked sideways... I've patched it into zaptel-1.2.15, and 
installed it and so-far so good! What was really weird before was that I 
would nearly always get the correct CID when I was called from a mobile 
(07...) but hardly ever from an 01 or 02 landline. However, 8 test calls 
later (2 x mobile, 2 x landline, 3 voip->pstn services and BT ring-back) 
and it's going OK.

> If you want UK caller ID _outbound_ on your FXS modules as well you'll
> have to wait a bit longer. I have a patch but it's not quite ready to
> party yet.

That's less of an issue (for me) - I'm guessing that most UK analogue 
phones with CID display will support *anything* that the telco throws at 
them, probably as BT, Telewest/NTL/Virgin Media (?) all seem to be 
different (and I always thought Telewest used Bell until I found one that 
does a polarity reversal recently!) ... I've never had a problem sending 
CID data to an FXS connected analogue phone with a display. (And to my 
surprise, I found my 5 year old NTL DECT set supported alpha characters as 
well as digits!)

Many thanks,

Gordon