[Asterisk-Users] FXO interfaces used in UK?

[Rich Adamson]

> Impedance setting in the UK!?  OK, I've clearly missed something along the way.  A search 
on the Wiki says something about Zcomplex impedance but I have absolutely no idea where or 
what this is.  If someone could point me in the right direction I'd be extremely grateful.
> 

That essentially means that not all telephone companies throughout 
the world are the same. The UK has its standards, the US has theirs, 
etc, etc. Your * fxo interface has to connect to the telephone 
company's pstn and use matching parameters "if" you want your fxo 
interface to work correctly. If they don't match you're likely to
incur echo, weird signaling problems, etc.

The standards often times include such things as the type of signaling
used on the pstn line, the impedence (600 ohms is the US standard) used
in designing the central office equipment and pstn cabling, etc.

The x100p fxo card is limited by the chip design on the card to US
standards, although some are using the card in the UK where different
standards exist.

The tdm04b (fxo) card uses a different set of chips, and has to be told
which international standard to use. Since * seems to default to US
standards, you will need to change that to uk standards. Might start by
reviewing the contents of /usr/src/zaptel/zaptel.conf.sample looking
for #loadzone=uk in that file. That file would have been copied to
/etc/zaptel.conf on your system when you installed asterisk.

Rich