I can give you more detailed information on that.
In situations where the data we receive is problematic, clients are given a notification. In the case of an ETA, for instance, applicants who do not receive a favourable decision online right away will be advised to contact the visa office in their country to speak with a Canadian officer. Under the ETA system, we anticipate that cases where an immediate response cannot be provided will automatically be referred to a triage centre in Ottawa, which will check the information against other databases. The purpose will be to determine whether a manual clarification is possible with the help of our partners.
If it is not possible to give the client a favourable decision within 72 hours, the individual will be invited to an interview with an officer overseas, in order to seek further details and determine whether things can be clarified and the problem straightened out. If so, the officer will grant the ETA. Otherwise, the client's application will be rejected, as is currently the case for some visitors. The reasons for the rejection will be shared with the applicant, who will have an opportunity to provide further information to an officer overseas.