Customize Modem Tone Detection Settings

You can optionally customize the default modem tone detection settings by creating a custom CSV file, which the SBC loads on startup to replace the default specifications.

You can use the custom CSV file to:
  • Customize tone specifications for frequency, duration, and signal level for most modem tones.
  • Disable specific tone detection.
  • Customize the default value of the tone detection timeout.

Note:

In HA deployments, you must add and edit the file on both the active and standby system, and reboot both. The file from the active system is not automatically synchronized to the standby system.
  1. Create a file called user_tones.csv.
  2. Do any of the following:
    • Customize specifications by adding lines in the following format:
      name,frequency1,frequency2,duration,signal_level
      where:
      • name is the name of the tone you are customizing. The following are supported:
        • Modem-Ans-Bell103
        • Modem-Ans-V21High
        • Modem-Ans-V23High
        • Modem-Ans-V22
        • Modem-Ans-V22+1800Hz
        • Modem-Ans-Baudot
        • Modem-Orig-Bell103
        • Modem-Orig-V21Low
        • Modem-Orig-V25Calling
        • Modem-Orig-V8bis
        • Modem-Orig-Baudot
        • Modem-Ans-V8bis
      • frequency1 is the first tone frequency, in Hz
      • frequency2 is the second frequency in Hz. This is optional, used only for dual-tone detection.
      • duration is the tone duration, in milliseconds
      • signal_level is the minimum signal level in decibel-milliwatts (dBm0)
    • Disable specific tone detections by adding specifications lines for them with either frequency and dual_tone_frequency or duration set to 0.
    • Customize the tone detection timeout value by adding a line in the following format:
      Timeout,NNNNN

      where NNNNN is the new timeout value, in milliseconds. The default value is 30000 ms. This value controls how long tone detection is enabled in a call. After this time has elapsed in a call, tone detection is no longer enabled for that call.

  3. Save and close user_tones.csv.
  4. Upload user_tones.csv to the code/media directory of the SBC.
  5. Reboot the SBC.

For example, to set the default timeout value to 60000 ms, disable the Bell103 tone from the answerer (by setting frequencies to 0) and originator (by setting duration to 0), and change the v.25 calling tone detection to 1305 Hz, with a 100 ms duration, and a minimum signal level of -20 dBm0, you would add the following content in the CSV file:

Timeout,60000
Modem-Ans-Bell103,0,0,100,-30
Modem-Orig-Bell103,1270,0,0,-30
Modem-Orig-V25Calling,1305,0,100,-20