Asterisk MoH Sound Quality

Posted on 2008-06-19
Last Modified: 2013-11-12
Every time I convert either a WAV or MP3 file to GSM using sox the sound quality drops drastically.  I have even tried to convert the file to GSM using an audio converter but stil no luck. Our PBX is asterisk v1.2 based.  Any suggestions on how to make Music on Hold not sound like it is distorted?  Thanks in advance.
Question by:sharpC
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 4
  • 3
LVL 36

Expert Comment

ID: 21829089
If you playback the converted file on a pc does it sound correct?

Have you tried reducing the volume during the conversion process?
Normally on hold music is quieter than voice so it is normal to reduce the volume.

Author Comment

ID: 21830954
On my pc recording sounds great.  And yes, I have tried reducing the volume.  In addition, I have tried saving it to various file formats using Adobe Audtion but still sounds like my sound clip has become synthesized.  Any other suggestions?
LVL 36

Expert Comment

ID: 21831222
gsm is a compressed format so it wont sound perfect. Certenly if you are listening to it on a pc it will be a vast difference in quality. Using a telephone handset it should be less noticeable though.

Maybe gsm is not the best format. Over what sort of connection are people going to be hearing the music on hold?
NEW Veeam Agent for Microsoft Windows

Backup and recover physical and cloud-based servers and workstations, as well as endpoint devices that belong to remote users. Avoid downtime and data loss quickly and easily for Windows-based physical or public cloud-based workloads!


Author Comment

ID: 21832546
I "think" you are asking me about my PBX.  We use an asterisk v1.2 server connected through a T1. Sorry if I am being dense.
LVL 36

Expert Comment

ID: 21832748
Is the T1 offering a primary rate telephone service or are you using voip over it?
If you are using voip do you know what codec you are using? (ulaw/alaw (g711), gsm, g723 etc...)

Author Comment

ID: 21856823
I had to verify settings with our vendors.  T1 is VoIP and our PBX is using:     G711 codec to transmit audio.  In the case of remote users where the Low Bandwidth Codec option is checked, the pbx will use the G729 codec
LVL 36

Accepted Solution

grblades earned 125 total points
ID: 21858034
In that case I would not convert it to gsm format. You are just converting to a lower quality more compressed format which asterisk will have to decompress to g711 or decompress and recompress back into g729.

You would be best off converting to .sln format (which us basically g711) using the instructions at :-

Featured Post

Independent Software Vendors: We Want Your Opinion

We value your feedback.

Take our survey and automatically be enter to win anyone of the following:
Yeti Cooler, Amazon eGift Card, and Movie eGift Card!

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

There are no good configuration guides for HP-H3C router to LYNC on the web. :( Big statement, but we havent been able to find one yet. We did find the following document useful, but the information was not enough to use H3C router for use as a L…
Almost all Internet protocol telephones have built-in switches at the back that allow you to connect your personal computer to one port and use the other port to connect your phone to to a Cisco switch.   Why we need to connect the PC to the pho…
NetCrunch network monitor is a highly extensive platform for network monitoring and alert generation. In this video you'll see a live demo of NetCrunch with most notable features explained in a walk-through manner. You'll also get to know the philos…
This is my first video review of Microsoft Bookings, I will be doing a part two with a bit more information, but wanted to get this out to you folks.

691 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question