The interviewer usually logs out of Phone Participants (for example, when going on a break) in order to avoid accumulating idle time. Phone Participants calls ISessionEngine.CloseInterviewerSession, which in turn calls IDialingProvider.SignOff. This should effectively block until the dialer has signed-off the interviewer. SignOff should block, but at this stage, Phone Participants cannot handle a connect for the interviewer.

As discussed in Requesting a contact, the dialer can add the interviewer to a dialing group when Get is called. The interviewer should not automatically be added back to a dialing group unless Get is again called. This may not be enough to stop silent calls if the dialer is using a predictive algorithm that is expecting the interviewer to again become available.