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

2012-03-11 Thread Sebastian Arcus

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 - 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.


Thanks for any help,

Sebastian

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

2012-03-11 Thread Tzafrir Cohen
On Sun, Mar 11, 2012 at 12:05:48PM +, 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.co...@xorcom.com
+972-50-7952406   mailto:tzafrir.co...@xorcom.com
http://www.xorcom.com  iax:gu...@local.xorcom.com/tzafrir

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

2012-03-11 Thread Sebastian Arcus

On 11/03/12 14:07, Tzafrir Cohen wrote:

On Sun, Mar 11, 2012 at 12:05:48PM +, 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.


Thank you Tzafrir. I initially though that the signal being analog, it 
can't be encoded with a digital compression algorithm - but as config 
examples online kept on suggesting the setting - I thought I would try it.





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

2012-03-11 Thread Shaun Ruffell
On Sun, Mar 11, 2012 at 06:49:01PM +, Sebastian Arcus wrote:
 On 11/03/12 14:07, Tzafrir Cohen wrote:
 On Sun, Mar 11, 2012 at 12:05:48PM +, 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.
 
 Thank you Tzafrir. I initially though that the signal being analog,
 it can't be encoded with a digital compression algorithm - but as
 config examples online kept on suggesting the setting - I thought I
 would try it.

Hi Sebastien,

If for some reason you do need it to be in alaw, i.e. sometimes you
can get bettwe results when bridging to a digital line in alaw mode
if the audio is originally companded to alaw on the analog card, you
can use the 'companding' or 'alawoverride' module parameter
depending on the analog card that you're using.

There is an old open bug for this, DAHLIN-58 [1], which will require
a board driver / core of dahdi interface change to allow the board
drivers to be notified when the companding mode on a channel is
changed.

[1] 
https://issues.asterisk.org/jira/browse/DAHLIN-58?focusedCommentId=177136page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-177136

Cheers,
Shaun

-- 
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Digium, Inc. | Linux Kernel Developer
445 Jan Davis Drive NW - Huntsville, AL 35806 - USA
Check us out at: www.digium.com  www.asterisk.org

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

2012-03-11 Thread Sebastian Arcus

On 11/03/12 18:57, Shaun Ruffell wrote:

On Sun, Mar 11, 2012 at 06:49:01PM +, Sebastian Arcus wrote:

On 11/03/12 14:07, Tzafrir Cohen wrote:

On Sun, Mar 11, 2012 at 12:05:48PM +, 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.


Thank you Tzafrir. I initially though that the signal being analog,
it can't be encoded with a digital compression algorithm - but as
config examples online kept on suggesting the setting - I thought I
would try it.


Hi Sebastien,

If for some reason you do need it to be in alaw, i.e. sometimes you
can get bettwe results when bridging to a digital line in alaw mode
if the audio is originally companded to alaw on the analog card, you
can use the 'companding' or 'alawoverride' module parameter
depending on the analog card that you're using.

There is an old open bug for this, DAHLIN-58 [1], which will require
a board driver / core of dahdi interface change to allow the board
drivers to be notified when the companding mode on a channel is
changed.

[1] 
https://issues.asterisk.org/jira/browse/DAHLIN-58?focusedCommentId=177136page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-177136

Cheers,
Shaun



Thanks Shaun. I'll keep this in mind in case it is ever needed.


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