There are two parts: the frequency and cadence. The tones used under the regional tab are listed in the format:

frequency1,frequency2,...,frequencyn;cadence1;cade nce2;...;cadencen

There's a character limit of 127 characters, 6 frequencies and 6 cadences. The frequencies are listed in a format: Hz@dbm. The cadences are listed in the format length(time on/time off/freq).

For example, the default dial tone (USA) looks like:

350@-19,440@-19;10(*/0/1+2)

This means:

• Frequency 1 is 350 Hz @ -19 dBm
• Frequency 2 is 440 Hz @ -19 dBm
• There is one Cadence section.
  • It is 10 seconds long.
  • It is on "forever" (that's what the star is), it is never off (that's what zero means here), and it plays both tones 1 and 2.

Using a more complicated example, the SIT1 (Special Information Tone) tone using the deafult (USA again):

985@-16,1428@-16,1777@-16;20(.380/0/1,.380/0/2,.380/0/3,0/4/0)

Means:

• Frequency 1 is 985 Hz @ -16 dBm
• Frequency 2 is 1428 Hz @ -16 dBm
• Frequency 3 is 1777 Hz @ -16 dBm
• The cadence section is 20 seconds and sequentially plays frequencies 1, 2, and 3 for .380 seconds and plays nothing for 4 seconds.