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Asterisk "electrical buzz" noise issue on simultaneous outgoing FXO calls over AEX800 (FreePBX)

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Last Modified: 2012-07-07
Hello:

Running Freepbx (latest).

I have an AEX800 and have configured only 4 of the 8 channels.

Here is my dahdi-channels.conf file:
; Span 1: WCTDM/0 "Wildcard AEX800" (MASTER)
;;; line="1 WCTDM/0/0 FXSKS"
signalling=fxs_ks
callerid=asreceived
group=0
context=from-pstn
channel => 1
callerid=
context=default

;;; line="2 WCTDM/0/1 FXSKS"
signalling=fxs_ks
callerid=asreceived
group=0
context=from-pstn
channel => 2
callerid=
context=default

;;; line="3 WCTDM/0/2 FXSKS"
signalling=fxs_ks
callerid=asreceived
group=0
context=from-pstn
channel => 3
callerid=
context=default

;;; line="4 WCTDM/0/3 FXSKS"
signalling=fxs_ks
callerid=asreceived
group=0
context=from-pstn
channel =>   => 4
callerid=
context=default

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Asterisk see's the channels:
localhost*CLI> dahdi show channels group 0
   Chan Extension  Context         Language   MOH Interpret        Blocked    State    
      1            from-pstn       en         default                         In Service
      2            from-pstn       en         default                         In Service
      3            from-pstn       en         default                         In Service
      4            from-pstn       en         default                         In Service
localhost*CLI>

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I have created one trunk (4 channels) called DAHDI, and reference it in my outbound routes. It is using g0 (see above.)

When I place a outbound call, the sound on the first call is crystal clear. However, when I place a second simultaneous call (and third, fourth), I hear an electrical buzz. The simultaneous calls do go through the correct channels, however all I hear is the above mentioned electrical buzz.

I will also mention that multiple incoming calls do not experience this problem.  Only outgoing.

Any thoughts on what I'm doing wrong?

You can hear the noise by calling +1 301 262 8282 - this hits a ring group which then tries to forward the call out on another channel.

Banging my head against a wall.

Phil
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Commented:
Phil,

     First you should use Capital G0 not Lowercase g0.  This way your outbound calls will use channels 4 -1 while your inbound calls assuming you have the four lines in a telco provided circular hunt group will come in 1 - 4.

     Second the hum you describe is usually (not always) a bad a cable or punch down on the Telco trunks coming into the System. Blending tip & ring will cause this.  Try putting an old analog phone or butt set on the RJ-11 that inserts into the card and see if the noise is there.

       Good Luck --

Author

Commented:
No noise on the lines at all.

I'm using freepbx.  I'll make that change and see what happens.

Author

Commented:
Unfortunately that didn't work.  I'm thinking the device is bad.

You can hear the "noise" I'm referring to by dialing +1 301 262 8282.  When calling that number, we're routing back out over the FXO port to a remote DID.
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Commented:
Okay, you could have a cold solder joint on the board.  

 But two other things is the country code correct.

  Unplug various lines from the card and try different combinations of the four cables in the card.  It could be a short or bad punch that only shows when multiples of the 4  lines are in use.  Which reminds me does it hum when you call out from an extension on the system ?

I will check back in the morning and see how you are making out, but it's midnight here now.

-----------------------

Author

Commented:
This issue only occurs when simultaneous outbound calls are made.  It does not occur for the first call made out, but each subsequent call.  This issue does not occur when simultaneous inbound calls are made,
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Commented:
Sounds more like hardware then.  

Might have a look through this two pages and make sure you are clean though in the configuration..

http://www.voip-info.org/wiki/view/DAHDI

http://docs.tzafrir.org.il/dahdi-tools/
Sections 2.5  & 2.4.7

By the way I never use cards. I much prefer one on the many ATA units on the market. Like the SPA 400 or now owned by Sangoma, Vega Series appliances or an AudioCodes MP- series unit.

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Commented:
Glad you found it --

Author

Commented:
Because it was the solution.
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