Restaurant no-shows concentrate exactly where they hurt most: Friday and Saturday evenings, at peak covers, on the tables you turned other guests away for. A four-top that does not arrive at 8:30 PM on a Saturday is not a small loss — it is the best table-hour of your week, gone.
Weekday lunch no-shows barely matter. Weekend dinner no-shows are the whole problem, which usefully narrows what you need to automate.
Call in the afternoon, not the day before
The right window is 2 to 5 PM on the day of the booking.
Early enough that a cancellation can be resold to a walk-in list or a waitlist. Late enough that the guest knows how their evening looks. A call the previous day gets a "yes" that means nothing, because plans change on the day.
Keep it to twenty seconds
This is the shortest call in this entire series, and it should stay that way. A guest who booked a table does not want a conversation. Confirm, offer the exit, end.
Ask about party size
A booking for six that arrives as three costs almost as much as a no-show, because you held a large table and turned away two smaller bookings for it.
Guests will rarely call to say the number dropped. They will happily tell you when asked. That one question probably recovers more covers than the no-show prevention does, and nobody thinks to ask it.
Do not upsell
The temptation is obvious — while we have them on the phone, mention the new tasting menu. Resist it entirely.
The call works because it is short and useful. The moment it becomes a marketing call, guests stop answering it, and you have lost the confirmation channel to gain nothing. Save the menu for when they are seated.
What it costs
Twenty to thirty seconds is around ₹2 per booking. A restaurant taking 60 weekend bookings spends ₹120 a night. One recovered four-top covers that many times over.
For most restaurants the honest recommendation is to call only weekend dinner bookings and large parties on weekdays. Calling every lunch two-top is spending money to solve a problem you do not have.
The version that matters more
The same call, run the morning after, asking one question about how the meal was — that is a feedback call, and it is worth more than the confirmation call for a restaurant trying to build a reputation.
Guests who had a good time will say so, and can be pointed at a review platform. Guests who did not will tell you privately rather than publicly, which is a considerably better outcome than reading it online three days later. Feedback calls covers how to run those without being annoying.