On Sun, Mar 11, 2012 at 06:49:01PM +0000, Sebastian Arcus wrote: > On 11/03/12 14:07, Tzafrir Cohen wrote: > >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. > > 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=177136&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-177136 Cheers, Shaun -- Shaun Ruffell Digium, Inc. | Linux Kernel Developer 445 Jan Davis Drive NW - Huntsville, AL 35806 - USA Check us out at: www.digium.com & www.asterisk.org -- _____________________________________________________________________ -- Bandwidth and Colocation Provided by http://www.api-digital.com -- New to Asterisk? Join us for a live introductory webinar every Thurs: http://www.asterisk.org/hello asterisk-users mailing list To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-users
