Calibration mode is a means to determine the optimum AMD parameters. In calibration mode, all calls are connected to interviewers (just as when AMD is disabled). The AMD measures the duration of the respondent's initial greeting. During this phase, the interviewer can hear the respondent, but cannot talk. When the AMD measurement is finished (end-of-voice), the interviewer hears a short beep (WBeep) and audio is connected in both directions.

In cases of long initial silence (longer than coff seconds) or persistent voice (longer than con seconds), the AMD measurement is aborted and audio is connected in both directions. This makes it possible to try out different values of db and qoff without losing the contacts.

The greet time measured by AMD is sent to the application and recorded in call.log. To determine the reliability of a given max setting for the AMD call dispositions, make a frequency distribution of the call outcomes according to the following table:

[1] greet=0 can be an artifact from using a too small coff value, such that the AMD measurement was abandoned before the greeting started.

[2] greet=0 starts playback of amfile, but possibly too early, before the answering machine is ready to record it.