Music on Hold Sources

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Music on hold (MoH) is recorded music that callers listen to while waiting on hold. It is used to avoid silence on the line and is used in several places of the system: when a call is on hold and when a caller is waiting in an agent group queue. The system allows three different source types for its music on hold: file, wave input, and RTP stream. These sources serve different purposes and are detailed below. The sources can be used in parallel in different locations on the same system.

  • Files: The system can use one or more files for MoH. These files are read by the system on demand and are played in an endless loop. Files must be placed manually into the audio_moh directory of the system. Although files are loaded only once, long files will be read into memory and can consume a lot memory space. Keep in mind that each minute of the file will require about 1 MB of memory space, so a 7-minute file will take up about 6.7 MB (128 kbit/s * 7 * 60 seconds). After it gets past the initial hick-up (jitter), subsequent calls to the MoH file will be smooth.
Format: Files must be in 8-kHz sampling frequency, and they should be in 16 bit per sample signed format. The format must be mono WAV. You may also use other formats (u-law and GSM), but these formats will have less audio quality and require more CPU performance.
  • Wave input: In Windows, snom ONE can read MoH from an audio input jack, which is a convenient way to connect a CD, MP3 player, or a radio to the system. The disadvantage of this method is that only one external music source can be used. You can also internally loop the audio output of the local computer back to the audio input of the computer. This allows you to use an MP3 player running locally to provide a large number of MP3 files. However, we recommend keeping an eye on the memory usage of the MP3 player, as some players have memory leaks and slowly consume the memory of the computer. MP3 and WAV files can be converted to the required format. See also Creating WAV Files for Music on Hold.
Note: This feature is currently available only for Microsoft Windows-based operating systems. The appliance uses the RTP streaming mode for the audio input jack.
  • RTP stream: Streaming RTP data is a popular way of providing music from external sources. As with a telephone conversation, the system receives the audio data in a standard RTP stream. Several external tools are available that are able to generate a compliant RTP stream. Because the system can have several RTP streams, you can use this method to generate different music on hold sources for the system. See also Paging and Music on Hold Application and Streaming VLC and snom ONE.
Format: The RTP stream must use G.711 encoding. No SIP signalling is involved with this method, and the system does not send RTP data back.
Important: Be sure to specify the port on which the system should listen for RTP input (e.g., 42000). This port must be available on the system. If you change the setting, you might need to restart the system service so that the change takes effect.

Configuring Music on Hold

MoH sources are available to all domains on the system, so setup is done from the administrator level.

  1. Navigate to Admin > Settings > MoH.
  2. Populate the fields using the following information:
    • Name: Assign a name to the MoH source (this name will appear in the Available Sources list at the end of this exercise).
    • Type: From the dropdown, choose the type of MoH that you will be using.
    • Domain: From the Domain dropdown, select your domain.
    • Filename: This field depends on which type of MoH you are using:
      • File: If you are using files, upload the file by clicking Browse. (Once the file has been uploaded, it will automatically get filed in the audio_moh directory.)
      • WAV Input: If you are reading MoH from an audio input jack, the Filename field will disappear.
      • RTP Stream: If you are streaming RTP data, enter the port on which the system should listen for RTP input (e.g., 42000). This port must be available on the system. If you change the setting, you might need to restart the system service so that the change takes effect.
  3. Click Create. The new source will be listed as an available source.
  4. To verify that the source has been added on the domain level, navigate to Domain > Settings. You should see the newly added source in the Music on Hold Source dropdown:

    Once MoH has been created, it can be selected for use on the domain within both the agent group and hunt group accounts.