How long does it take for Air China to issue SMS instead?

Three minutes. Flight changes are a common phenomenon. Many passengers can't take the flight according to the departure time marked on the ticket because of work or other reasons after purchasing the ticket in advance. At this time, they can change their tickets (or refund their tickets). The sooner you change tickets, the lower the handling fee. It is very convenient to change the visa. A few minutes after the application is submitted, the change will be notified.