How it works
Yes, and for most appointment businesses it converts better. A missed-call SMS starts a thread the caller cannot easily continue and you cannot easily automate. A WhatsApp reply lands in an app they already use, supports a real back-and-forth, and can carry the booking to completion rather than just apologising.
When a call goes unanswered, the system automatically sends the caller an SMS — usually something like "Sorry we missed you, how can we help?". It is a well-established tactic because it catches people at the moment of intent instead of hours later.
The idea is sound. The channel is the part worth questioning.
Because the conversation can actually continue. SMS replies land in an inbox nobody monitors, threading is unreliable, and the exchange usually collapses back into a phone call — which is where the problem started.
On WhatsApp the client is in an app they check constantly, the thread persists with full history, and the reply can do real work: quote a price, offer two specific times, take the booking, confirm it. The difference is between acknowledging the missed call and recovering it.
Two pieces. Something that detects the missed call, which is a function of your phone system or your mobile provider. And a WhatsApp number on the WhatsApp Business Platform that can send the first message and handle whatever comes back.
One rule worth knowing before you build it: an outbound message you start yourself falls outside the free 24-hour customer service window, so it is a chargeable message under Meta's rules. Replies within the window that the client opens by messaging you are treated differently. Budget for the first message, not the conversation.
Not an apology. The strongest version answers the likely question immediately and offers a next step: what you do, roughly when you are free, and an invitation to say what they need. "Sorry we missed your call" makes the client do the work again.
Then the reply has to be handled. A missed-call message that starts a conversation nobody answers is worse than no message, because you have now visibly ignored them twice.
Common questions
The trigger usually depends on your phone system. The WhatsApp message is a business-initiated message outside the free customer service window, so Meta charges for it under its current published rules. Srileo passes those fees through at zero markup.
Rarely, if it is useful and immediate. People dislike being sold to; they do not dislike being answered thirty seconds after they tried to reach you.
That is the point of using WhatsApp rather than SMS. Elily can answer the follow-up question, check live availability and book the slot in the same thread.
No. It works on your business's own WhatsApp number through the official Business Platform, so the client sees the number they already called.
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