If you are using Delacon's call feedback feature, the survey is initiated automatically when the caller disconnects. In order to initiate the survey before the caller disconnects, a dedicated cut key can be configured. When the cut key is pressed, the caller will be disconnected and the feedback survey will begin.
The Cut Key can be configured in the Delacon portal by visiting Menu > Services > Edit > Cut Key
Please note, in order to use the cut key, you will also need to set the DTMF intercept to "1" as described here.