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Music on Hold Quality - IP Telephony

Posted on 2011-03-24
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Last Modified: 2012-05-11
This is more of a general question, but I have a local PBX (Zultys MX250) that allows for music on hold.  The quality of the playback is utter crap, but only when you call in from the street. I've noticed that this seems to be fairly common with ANY phone system, but any suggestions would be great The source is a wav file held on the PBX itself and originated as an mp3 (an original by a coworker) that I used audacity to convert to:

Microsoft Wav (Header)
U-Law codec
8000 hz
mono
8 bit
 
We're US (T1) so I assume we us u-law (I've read that a-law is used on E1 circuits).  
Any ideas?  Would it make any difference using a different program to encode?
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Question by:JamesonJendreas
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Merete earned 500 total points
ID: 35213409
How does the mp3 play?
Why it is worse when the call is closer is probably just that !!! closer indicates a stronger signal.

Converting from mp3 to wav it's using Microsoft windows wav format not a true U-Law codec, Audacity is great make sure your using the latest versions
resample the wav into 16bit mono 8khz
or 8 bits mono 8khz
http://www.videohelp.com/tools/OGG_Vorbis_ACM_Codec
 Goldwave maybe better.
http://www.goldwave.com/features.php

This is a reference to compare the monophonic (not stereophonic) audio quality and compression bitrates of the different codecs available for .wav files including PCM, ADPCM, Microsoft GSM 06.10, CELP, SBC, Truespeech and MPEG Layer-3.
http://en.wikipedia.org/wiki/WAV#WAV_file_compression_codecs_compared

Music On Hold Wav
http://www.musiconholdinfo.com/on-hold-music/music-on-hold-wav/

Gspot is an excellent free tool to analyse the codecs in audio and video when you wish to see what is inside
http://www.videohelp.com/tools/GSpot
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by:JamesonJendreas
ID: 35218223
I used audacity to convert the MP3 to a u-law WACV actually - the system won't take a wav that is not properly encoded.

Anyway, I'm going to take a look at those links to see if they can help me out.  Also, since my system allows for a 3.5mm input, I'm going to throw my Zune on it and see if that playback has any better quality.
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Author Comment

by:JamesonJendreas
ID: 35218233
That should be "wav" not WACV.  Alos Gspot is a tool I use often and can cinfirm my codecs are u-law.
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