[Asterisk-Users] Echo on one E1 line, but not the other

[Steve Hanselman]

More by trial and error, we backed off the gain until it disappeared but
with no detriment to the call quality (didn't want people to sound like a
whisper).

Our situation was somewhat different to yours though, we were seeing the
issues on calls from our PBX, not on calls through the IP phones.

Who hears the echo, the IP phone user or the remote user?

Steve


-----Original Message-----
From: Asterisk [mailto:Asterisk at dotr.com] 
Sent: 13 December 2004 12:36
To: 'Asterisk Users Mailing List - Non-Commercial Discussion'
Subject: RE: [Asterisk-Users] Echo on one E1 line, but not the other

Both ISDN lines are going into the same * box - span 1 is the "test" isdn
line and span 3 is the "live" isdn line. The two ISDN lines are situated
right next to each other!

As mentioned there is no problem with the test line, so there isn't a
problem with * as such (I don't think!). Perhaps I haven't got the
configuration quite right. 

When you say that you adjusted the gain, is that the tx/rx settings in
zapata.conf ? How did you determine the correct settings: by placing a call
and monitoring using ztmonitor ?

Thanks.

Julian

-----Original Message-----
From: asterisk-users-bounces at lists.digium.com
[mailto:asterisk-users-bounces at lists.digium.com] On Behalf Of Steve
Hanselman
Sent: 13 December 2004 12:13
To: 'asterisk at dotr.com'; 'Asterisk Users Mailing List - Non-Commercial
Discussion'
Subject: RE: [Asterisk-Users] Echo on one E1 line, but not the other

It looks like this is a splice between a couple of ISDN-30 lines and one or
more PBX's?

Are they both with the same provider, or with different providers?

We ended up adjusting the gain our ours as we would hear a distinct echo on
certain calls.

Other than that, you'll need to do the usual tests, check for shared
interrupts, also, see if disk activity causes a problem.

(check /proc/interrupts for shared interrupts).

Have you also checked the output of the pri commands to ensure that you're
not getting line errors?

Steve


-----Original Message-----
From: Asterisk [mailto:Asterisk at dotr.com]
Sent: 13 December 2004 12:04
To: 'Asterisk Users Mailing List - Non-Commercial Discussion'
Subject: [Asterisk-Users] Echo on one E1 line, but not the other

We're rolling out Cisco 7940 phones, linked to *, which is running a TE405p
EuroISDN.

We have 2 ISDN lines, one we had for testing, and one for general (40+
users) use.

During the testing phase, we had 10 phones linked to the second ISDN line,
and there were no problems with echo at all. Lucky me. However, since we
have started rolling out, we've had quite loud complaints that there is "a
terrible echo". If I direct my 7960 to use the primary line, there is an
echo. If I use the second line (dialling the same external number) there is
no echo at all.

What could be the issue ? I have noticed on the primary line there is a
"detected rx/tx on channel xx, echo cancellation disabled" (or something
like that. Is this the cause ? We have several fax / modems going through
the line - should I always dedicate a channel to them ?

I've included my zaptel.conf and zapata.conf file below. Any help / comments
appreciated.

#
# Zaptel Configuration File
#
# This file is parsed by the Zaptel Configurator, ztcfg #

span=1,1,0,ccs,hdb3,crc4
bchan=1-15,17-31
dchan=16

span=2,0,0,ccs,hdb3,crc4
bchan=32-46,48-62
dchan=47

span=3,2,0,ccs,hdb3,crc4
bchan=63-77,79-93
dchan=78

span=4,0,0,ccs,hdb3,crc4
bchan=94-108,110-124
dchan=109

loadzone=uk
defaultzone=uk

#############################################

;zapata.conf

[general]

[trunkgroups]

[channels]
musiconhold=default
language=en
rxwink=300		; Atlas seems to use long (250ms) winks
usecallerid=yes
hidecallerid=no
callerid=asreceived
callwaiting=yes
usecallingpres=yes
callwaitingcallerid=yes
useincomingcalleridonzaptransfer=yes
threewaycalling=yes
transfer=yes
cancallforward=yes
callreturn=yes
echocancel=yes
echocancelwhenbridged=yes
echotraining=yes
echotraining=800
;relaxdtmf=yes
rxgain=0.0
txgain=0.0
;callgroup=1
;pickupgroup=1
;adsi=yes

context=isdn32-b
pridialplan=unknown
group=1
signalling=pri_cpe
switchtype=euroisdn
channel=1-15,17-31

context=meridian-b
group=2
signalling=pri_net
switchtype=euroisdn
channel=32-46,48-62

context=isdn32-a
pridialplan=unknown
group=3
signalling=pri_cpe
switchtype=euroisdn
channel=63-77,79-93

context=meridian-a
group=4
signalling=pri_net
switchtype=euroisdn
channel=94-108,110-124

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recipient then you are hereby notified that you have received this document in error and
that any review, distribution or copying of this document is strictly prohibited. If you have 
received  this communication in error, please notify Brendata immediately on: 

+44 (0)1268 466100, or email 'technical at brendata.co.uk' 

Brendata (UK) Ltd
Nevendon Hall, Nevendon Road, Basildon, Essex. SS13 1BX  UK
Registered Office as above. Registered in England No. 2764339

See our current vacancies at www.brendata.co.uk