The data passing phase is optional and is in effect only if the application calls for the switch to pass information in-band to the VRU.
The converse-on step can outpulse up to two groups of digits to the VRU. The digits can serve two major purposes:
Notify the VRU of the application to be executed.
Share call-related data collected by the switch. This includes ANI, CINFO, or caller digits.
In many applications, both application selection and data sharing are required.