User's Manual

Voice API Programming Guide — June 2005 167
Global Tone Detection and Generation, and Cadenced Tone Generation
• To generate a continuous, non-cadenced signal, you can use dx_playtoneEx( ) and
TN_GENCAD to specify a single segment with zero off-time and with an infinite number of
cycles and/or an infinite on-time.
Alternatively, you could use dx_playtone( ) and TN_GEN to generate a non-cadenced signal.
The following non-cadenced call progress signals could be generated by the dx_playtone( )
function if you defined them in a TN_GEN: 1) Dial Tone, 2) Executive Override Tone, and 3)
Busy Verification Tone Part A.
• Note that the Intercept Tone consists of alternating single tones.
• Although the TIA/EIA Standard describes the Busy Verification Tone as one signal, the two
segments are separate tones/events: Part A is a single burst almost three times longer than Part
B and it alerts the parties before the attendant intrudes; Part B is a short burst every 9 seconds
continuing as long as the interruption lasts. The TIA/EIA Standard does not define an off-time
between Part A and B. Therefore, the application developer is responsible for implementing
the timing between the two parts of this signal.
• The TIA/EIA Standard specifies the range of permissible power levels per frequency for 1) the
Central Office trunk interface and 2) all other interfaces (including off-premise stations and tie
trunks). The Intel implementation adopted the approximate middle value in the acceptable
range of power levels for applying the signals to the CO trunk interface. These power levels
were more restrictive than those for the other interfaces. According to the following statement
in the TIA/EIA Standard, additional requirements and considerations may apply:
“Studies have shown that the lower level tones that are transmitted over trunks should be 6 dB
hotter at the trunk interface (than at the line interface) to compensate for increased loss on the
end-to-end connection. In the case of tones used at higher levels, the 6 dB difference is not
used since power at trunk interfaces must be limited to -13 dBm0 total when averaged over any
3-second interval to prevent carrier overload. Maximum permissible powers listed are
consistent with this requirement taking into account the allowable interruption rates for the
various tones. Uninterrupted tones, such as Dial Tone and Intercept Tone, shall be
continuously limited to -13 dBm.”
For related power level information, see also Note 1 for Tables 29 and 30, Section 5.9, and
Section 6.3.5.