No there is no arrangement. They will just call your relative based on the telephone number that you have provided in your application. I cannot recall if it was done during office hours or after. The questions are quite basic like what is the full name of the applicant, how long have you known each other, when was the last time you talked to each other, etc. In other forum threads there is a more comprehensive/detailed list of what was asked during the interview that was posted recently.