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Detailed Call Flow for Converse—VRI Calls
H-8 Issue 4 September 1995
The CONVERSANT VRU offers a built-in external function called
‘‘converse_data.’’ This function allows applications developers to perform this
operation in a convenient and robust fashion.
To ensure the robust operation of the VRU data return operation, be sure to follow
these recommendations:
■ Set the analog flash timing to 600 msecs
■ Ensure DTMF tones last at least 70 msec
■ Ensure interdigit pauses last at least 50 msec
■ (CONVERSANT only) Use the ‘‘converse_data’’ external function to return
data to DEFINITY
For applications involving VRUs other than CONVERSANT VRUs, be sure to
follow these recommendations:
■ After the flash, ensure the VRU performs dialtone detection (stutter
dialtone) for five seconds before outpulsing the converse data return
feature access code.
■ If no dialtone is received before the timeout, ensure the VRU does two
more retries of the analog flash. Also, if no dialtone is detected after two
retries, ensure the VRU logs an error.
■ Whenever dialtone is detected, ensure the digits of the converse data
return feature access code are outpulsed.
■ After the converse data return feature access code is outpulsed, ensure
the VRU performs dialtone detection (steady dialtone) again for five
seconds before outpulsing the returned digits. If no dialtone is detected,
ensure an error is logged by the VRU.
■ Whenever dialtone is detected, ensure the VRU digits are outpulsed and
the line to DEFINITY is dropped.
The TN744 Call Classifiers required by the Call Prompting feature are not
required for returning digits in-band from the VRU to DEFINITY. Instead, general
purpose TTR boards (TN748s) are used. As long as dial-ahead digits are
available, any
collect digits
steps following a
converse-on
step do not require a
TN744 to be allocated to the call.
If no general purpose TTRs are immediately available, and if the call queues for a
TTR, no dial tone is provided. For this scenario, the VRU does not outpulse any
digits until a TTR is available and dial tone is provided.
If there are no general purpose TTRs available on DEFINITY, and if there is no
space in the TTR queue, the operation fails. Usually, the VRU logs an error and
then quits, and vector processing continues at the next vector step. Existing
system measurements reports inform customers when the system is configured
with an insufficient number of TTRs.