Thank you for your help.
I downloaded firmware and sample configuration files.
But the firmware was old version for MP118 and MP124.
Jason.
Jason,
First, before you start reading, get to the latest
firmware from
Audiocodes (MP118_SIP_F4.80A.034.004.cmp), there
have been
significant echo improvements in this version.
After many days of working with Audiocodes on this
problem and much
time spent here by multiple technicians trying to
reproduce and
resolve this issue; this morning, Atacomm received
an email from
Audiocodes with a full explanation to this now
confirmed issue with
all MP-11x units. Atacomm will immediately begin
work on a KB article
within our website that confirms this issue and
outlines the
manufacturer recommended steps to resolve this
problem.
Apparently, there have been some changes with the
MP-11x's that can
negatively affect line noise and echo. Below are
some steps which
can help to correct these problems:
1. The new design did away with the Coefficent file.
Audiocodes, now
instead, introduced a configurable parameter called
countrycoefficient. This parameter can be adjusted
to a specific
country based on known configurations. For the most
part this should
work. 70(USA) is the default value. More can be
found in the User’s
manual.
2. In just about every case, an FXO is added to a
Pre-existing PBX
or CO line, you can expect echo. This comes from the
fact that delay
(IP Network) is being introduced, and what used to
be Side tone is
now delayed so much it is echo. Just about every
difference on the
line that can be heard between the pre fxo and post
fxo installation
can be traced to echo, or line quality issues.
3. Going forward, Audiocodes would like to suggest
that when
installing the product do the following:
A) Make sure the Line coming from the PBX or CO is a
Loop Start line.
Ground start is not supported on the MP-11x series
of gateways. (The
M1K FXO will in 5.0)
B) Check that the Line can deliver for a 600 Ohm
Impedance line
-52 to -24 V of Off Hook Voltage
-15 to -6 V of On Hook Voltage
20 to 35 ma of loop current.
If you know the line is not 600 Ohm, please gather
metrics on the
line, and the make and model of the PBX or switch it
is attached too,
plus country of origin. If it is not from the USA,
please look up the
country of origin and then find the
CountryCoefficient to match this.
Load the .ini file to the board with this setting
and reset. Make
sure the Gateway has a firmware version of 4.60.035
or higher or
4.80.030 or higher.
C) Put the device on the network with Voice Volume
set to 0 and input
gain set to 0. Make calls, if there is no issue, you
can stop here.
However, Echo is still expected most of the time.
D) The echo should be heard by the IP side
participant as their voice
is reflected back. If this is the case, then what
needs to be done
is to lower the voicevolume (IP—TEL). This way the
speaker’s
reflected voice will comeback low enough for the
ECAN to cancel it
out (-6 is usually recommended as the value to plug
in here). A
little experimentation is needed as the loss for all
lines will vary
based on length from the CO. Echo is usually taken
care of in this
manner.
E) The incoming speaker from the PSTN’s voice seems
low, set
InputGainLocation =1, and then slowly increment the
Input Gain
Parameter(Tel?P) to adjust for this. In past
releases (see the note
about loads above), the input gain was always
applied prior to the
ECAN which had the effect of amplifying the returned
echo and noise
on the line causing crosstalk and clipping issues.
This is no longer
the case.
If the above does not resolve the issues, then you
need to go ahead
and collect DSP, Ethereal and Syslog traces along
with the board.ini,
these are to be sent to your support agent, who will
then send these
to Audiocodes for their engineers to evaluate. This
should not
happen often.
Jessee Holmes
Atacomm / Ataractic Corporation
www.atacomm.com
V: 1-877-700-VOIP
Looking for voice over IP products? Visit our VoIP
store at http://
voipstore.atacomm.com/
On Nov 3, 2006, at 12:14 AM, Jason Kim wrote:
Jessee,
I tried many combinations of "Voice Volume", "Input
Gain" and packetization time , but it's noisy steel.
I'm using G.711A-law and packetization time is 20ms.
It can be impedance mismatch problem but i cannot
adjust impedance of FXO port of MP-114.>
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