[asterisk-users] "alaw = 1-2" in system.conf (dahdi) not working in UK

Tzafrir Cohen tzafrir.cohen at xorcom.com
Sun Mar 11 09:07:16 CDT 2012

On Sun, Mar 11, 2012 at 12:05:48PM +0000, Sebastian Arcus wrote:
> Hi all,
> I've tried to explicitly set my two PSTN trunks/FXO lines to alaw with:
> alaw = 1-2
> in /etc/dahdi/system.conf. However, when I do this, all I get is
> loud intense noise on the line and nothing else - can't dial, can't
> make calls, can't receive calls. If I omit it altogether, everything
> works fine.
> As I'm in the UK - I thought Europe uses alaw on phone lines

No, they don't. Phone lines are analog. ulaw / alaw settings here are
internal to DAHDI. The digital PCM gets converted to analog "audio"
(voltage level) on the adapter.

>- how
> come Asterisk seems to be using only ulaw - and alaw won't even
> work? Config examples on the Internet seem to suggest that it should
> work.

Though it is, indeed, a bug.

               Tzafrir Cohen
icq#16849755              jabber:tzafrir.cohen at xorcom.com
+972-50-7952406           mailto:tzafrir.cohen at xorcom.com
http://www.xorcom.com  iax:guest at local.xorcom.com/tzafrir

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