How call progress tones are defined

Each tone is defined by the following parameters:

Example: How to work out maximum and minimum values from nominal values

To define a dual tone specified by the nominal values shown in Table 1, perform the calculations shown in Example call progress tone calculations to work out the maximum and minimum values:

Table 1. Example call progress tone nominal values.

This table describes for a dual tone, the nominal values of the frequency in Hz, level in dBm, time on and time off in ms for Frequency 1 and Frequency 2, where Frequency 1 is the lower of the two frequencies.

 

Frequency

Level

Time On

Time Off

Frequency 1

300 Hz

-18 dBm

250 ms

250 ms

Frequency 2

480 Hz

-18 dBm

250 ms

250 ms

Notes:
  1. For a dual tone, Frequency 1 must be the lower of the two frequencies. For tritones, Frequency 1 must be the first tone, Frequency 2, must be the second tone, and Frequency 3 must be the third tone in the sequence.
  2. Use 9% as a guideline only in calculating minimum and maximum frequency values. With smaller absolute numbers, a larger percentage should be used. Also, you need to ensure that the range specified by minimum and maximum values for one frequency do not overlap with that specified by the values for another frequency.
  3. All time values must be rounded to the nearest 20 ms.
    Example call progress tone calculations

    Frequency 1

    Frequency 2

    Minimum
    = 300 - 9% 
    = 300 - 27 
    = 273 Hz 
    Maximum
    = 300 + 9% 
    = 300 + 27 
    = 327 Hz 
    Minimum
    = 480 - 9% 
    = 480 - 43 
    = 437 Hz 
    Maximum
    = 480 + 9% 
    = 480 + 43 
    = 523 Hz 

    Level 1

    Level 2

    Minimum
    = -18 + (-6)
    =-24 dBm
    Maximum
    = 0 dBm 
    Minimum
    = -18 + (-6)
    = -24 dBm
    Maximum
    = 0 dBm 

    Time On 1

    Time On 2

    Minimum
    = 250 - 15% 
    = 250 - 38 
    = 212 
    = 200 ms
    Maximum
    = 250 + 15% 
    = 250 + 38 
    = 288 
    = 300 ms 
    Minimum
    = 250 - 15% 
    = 250 - 38 
    = 212 
    = 200 ms
    Maximum
    = 250 + 15% 
    = 250 + 38 
    = 288 
    = 300 ms 

    Time Off 1

    Time Off 2

    Minimum
    = 250 - 15% 
    = 250 - 38 
    = 212 
    = 200 ms
    Maximum
    = 250 + 15% 
    = 250 + 38 
    = 288 
    = 300 ms 
    Minimum
    = 250 - 15% 
    = 250 - 38 
    = 212 
    = 200 ms
    Maximum
    = 250 + 15% 
    = 250 + 38 
    = 288 
    = 300 ms 

Recognizing double rings

Two ring tones should be defined when a double ring tone needs to be detected. A double ring tone is one in which the ring sequence is: ring...short pause...ring...long pause. The sequence, however, might not start at the beginning, which means that what Blueworx Voice Response detects is: ring...long pause...ring...short pause. To detect either sequence, then, you must define two tones, each with the same frequencies and levels, but with different cadences. One is defined as the first portion of the ring (ring...short pause), and the other is defined as the second portion (ring...long pause). This enables faster, more efficient detection of double ring tones.