Version 15 and earlier would allow the import of unsupported Wav and mp3 files and convert them on the fly during playback. This process created high CPU usage and unnecessary threads so we removed this conversion. Prompt files need to be prepared correctly. We have found that many customers used unsupported prompts in their installations.  

These must be converted PRIOR to upgrading to SP2. (Available in the coming weeks)

You can prepare for this change by making the conversion now. Failure to do so will result in the prompt not being played, and callers calling will hear silence. 

All the 3CX supplied prompts are already in the correct format. You just need to convert the prompts you used for IVR, Queues and custom system prompt sets. 

Prompts need to be like this:

Format: WAV

Channel: Mono

Bit rate: 8 kHz

Sample: 16 bit

Convert a WAV file

To convert a file you can use a free tool like “Audacity”

  1. Download Audacity: and install it.
  2. Click on “File > Open” and locate the file you want to convert.

  1. On the left side you will see the current properties of the file. In this case the problem is that the bit rate is 16000 Hz, this has to change.

  1. Go to the “Project Rate (Hz)” dropdown and change to 8000.
  2. Click on “File > Export Audio” and the “Save As” dialog will appear.

  1. Enter a name and select “Save as type: WAV (Microsoft) signed 16-bit PCM”.
  2. You can now upload this file via the 3CX Management console. 

Convert an MP3 or Stereo to Mono Channel

If your WAV file is MP3 or Stereo, do the following: 

  1. After opening the file, click on the arrow depicted below. 

  1. Select “Split Stereo to Mono”.

  1. Close all the streams by pressing the “X” button next to the file name. 
  2. Modify the project rate to 8000 Hz and click on “File > Export Audio”.
  3. Enter a name and select “Save as type: WAV (Microsoft) signed 16-bit PCM”.