Does voice recording affect speech quality?

[Albus]

Hi all

I just want to ask for your experience with call recording (VoiceMail PRO). Maybe only together with IP-Phones and ISDN-Lines.

Problem: In the above setup when recording is active, the quality is bad.
There may be some echo as well as some strange noise. This can happen for the complete call or just for some parts of it. Also the intensity of this disturbance may vary from call to call. Another side effect is, that DTMF tones for a remote IVR have a strange sound. Some systems have no problem, but other IVR simply cannot decode the tones.

When recording is off, there is no problem at all.

As far as I can say, this does not happen to calls made with digital phones.


Do you know about similar issues?
It may also help to hear that others are using this witout problems.

I found only one post from PlatinumGuy: thread940-1415833 but this was in Oct '07 when 4.0 was out. I have it now with 4.2

 

[Westi]

http://www.tek-tips.com/viewthread.cfm?qid=1539313

another thread from a few weeks back (March 09)

http://www.tek-tips.com/viewthread.cfm?qid=1449725&page=10

this one is from Feb 08

seems to have a common problem, call recording is not good for voice quality.

Joe W.

FHandw., ACS

If you can't be good, be good at it!

 

[tlpeter]

What 4.2 do you have ?
There are 3 of them already.
And yes some versions do have some problems with call recording
Do you perhaps use contact store ?
Playing back with contact store doesn't give the best quality

ACS - Implement IP Office
ACA - Implement IP Telephony -- ACA - Design IP Telephony
ACA - Voice Services Management
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[Albus]

@Westi
I think you are right. "Call recording is not good for voice quality". Not good but true.

@tlpeter
We have this in several installations. All are IP500. Different releases up to the latest. IP-Phones are also on the release matching the IPO, same for VoiceMail PRO and ContactStore.
Whats common is: VoIP and recording.

This calls involve a VCM channels as well as the conference chip. And then there is this data cannel to the VM PRO.

AGC is off for handsets. We put this by default in the 46xxsettings.txt and it is the first to check when someone complains about quality.

ContactStore does not matter here. You will have the same just with VM PRO. CS is just for storing and easy access of the recordings. And it is compressed later on to G.726 which makes them lower quality when retriving a recording. But we have the problem during the conversation.

 

[Bas1234]

You could try to play with "Nonlinear Processor Mode"

Open the Manager;

System > VCM > Nonlinear Processor Mode > Silent

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It works! Now if only I could remember what I did...
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[kholladay]

It can but not always. If you have this issue it is a good sign that you may not have the proper equipment in place. I know that when we have used a server that wasn't up to spec for Contact Store, for example, that it caused our voice quality overall to be quite low both for the recordings and the speech while being recorded.

Kyle Holladay
ACA-I, ACA Call Center, ACS-I, ACS-M, TIA-CTP, MCP/MCTS Exchange 2007
ACE Implement: IP Office

"Thinking is the hardest work there is, which is the probable reason why so few engage in it." - Henry Ford

 

[kholladay]

Oh and by the way by "up to spec" I mean that we were trying to use the same hard drive for the software (VMP and Contact Store) as the recordings themselves and the disk I/O was just to much for the drive. When we did nothing more than add a second hard drive and point recordings to that drive it cleared things up.

Kyle Holladay
ACA-I, ACA Call Center, ACS-I, ACS-M, TIA-CTP, MCP/MCTS Exchange 2007
ACE Implement: IP Office

"Thinking is the hardest work there is, which is the probable reason why so few engage in it." - Henry Ford

 

[Albus]

We have norrowed the problem to be the conference chip.

Recording with VoiceMail PRO makes use of the conference chip. It is like a conference between the extension, the line and voicemail.
But this should make it easy to reproduce: Just have another extension in a conference and call an IVR. If you use an IP-Phone for this, it may fail. I have this for some calls to nortel ivr, but not generally to all systems.

I would be happy if someone can do this simple test if it fails, post the number for this ivr service.
Many thanks!

Voice quality may be bad too, but here you have to do some conversation over the lines and maybe mute the second extension. It is easier to test with DTMF.

 

[c0nverge]

yes it is the same and what really helped me was that in the "no user" 's source code you will need to make a new code which will help resolve the issue in 4.2.11
the code is " CONFERENCE_DSP_TX_GAIN=-2 "
this certainly solve the issue
for fine tuning vary the values from -10 to 0

 

[Albus]

There is no effect with this code. I was told to use -2 but there is no difference. Tried -10 to 0. No work.

I'm shure this is easy to reproduce. You need:
- IP500
- IP-Phones
- ISDN Lines (don't know about analogue, we don't have that)

Use the IP-Phone and have a conference with another extension or external line as well as an external phone.
Send DTMF from the IP-Phone and hear it on the B-party.
Repeat this in a direct call to the external B-party.

Don't you hear a difference?
It sounds strange and truncated.

 

[Albus]

Well, it is really not hard to do this test. And I'm happy that Avaya now could reproduce it finally. A fix is at work by development.
It should solve problems with bad voice for IP-Phones when conference is used.

 

[jeffthephoneguy]

Albus... did you ever get an answer/fix to this issue?