A customer was recently experiencing problems retrieving voicemails left by external callers. When playing back the recordings, the messages were distorted to the point where it was impossible to comprehend the information needed to return the call.
Researching into this, I discovered that in order to resolve the problem, the codec must be changed.
IP Office selects G.729(a) 8K CS-ACELP by default. This is one of the low bandwidth codecs. By changing this to G.711 ALAW 64K – one of the high bandwidth codecs – the problem can be easily solved.
- Open and log into IP Office Manager
- Select “System”
- Click on the “Telephony” tab
- Select “Telephony” again
- Go to “Automatic Codec Preference” and select G.711 ALAW 64K from the drop-down menu
- Click on “OK” and then on the disc to save the change
The system will then require a re-boot and NOT a merge. It is usually best to choose the “when free” option to ensure that the phone system will only reboot when it is not being used.
Users will then need to log back into their phones.
Once the codec has been changed, saved and the IP Office re-booted, all voicemails should be of a sound audible quality.

