You can get a call/email/letter for interview only if there are any discrepancies/doubt with your documents or information you provided on your application. There is an operational bulletin that guild the processing of the applications. Before CHC can refused an application after update and having necessary pass mark, CHC must undergo a procedural fairness, to invite the applicant(s) for interview to explain him/herself where CHC have noted a "comma". Instead of refusing bluntly, they will invite the applicant, a positive selection decission by VO rest solely on the applicant(s) during the interview, to convince the VO on the information or documents that needed to be clarified.
If all information, documents and having necessary pass mark seem ok for VO, then there will be an instant selection decission where at this time an interview is waived. Applicants will only know if interview is waived when he/she receives a medical request.