Chapter 1 · The scenario
Example: A radio spot for a coaching institute
A Jaipur coaching institute runs a 20-second radio spot: "Give a missed call to get this year's NEET batch timetable on WhatsApp." Within ten minutes of each spot the number takes about 1,200 calls. Each caller's number reaches the institute's webhook, is de-duplicated against the last 24 hours and receives an approved WhatsApp template with the timetable PDF and a "Talk to a counsellor" button. Callers whose numbers are not on WhatsApp — the template comes back undeliverable — get a DLT-registered SMS with a whitelisted short link instead, and every opt-in is stored with the spot that produced it.
Chapter 2 · What is a missed call service?
A missed call service is a phone number a business publishes so people can "give a missed call" to it. The platform behind the number lets the call ring, rejects it before it is answered and records the caller's number (the caller line identification, or CLI), the number dialled and the time. That single event triggers an action: an SMS with a DLT-registered template, a WhatsApp template, a callback from an agent or a new lead in a CRM.
The pattern became popular in India because it costs the caller nothing — an unanswered call is not billed — and works on every handset, including feature phones without mobile data. Banks use it for balance enquiries from a registered number, brands for contests and catalogues, civic campaigns for sign-ups, and lenders and schools for lead capture from print, radio and hoardings. Because the caller's network presents their number, the call also shows, weakly, that the person has the phone they called from.
It differs from click-to-chat, which opens a WhatsApp conversation the customer starts — and so a 24-hour customer service window — but works only for people with WhatsApp and data. A WhatsApp reply to a missed call is business-initiated: it must be an approved message template, it is charged per delivered message by category, and it needs a clear opt-in, so the poster or ad must say the caller will receive WhatsApp messages from the business. It is also the reverse of flash call verification, where the business calls the user.
Key takeaways
- A missed call service gives a number that rings, rejects the call and logs the caller's number, which then triggers an SMS, WhatsApp message or callback.
- The caller pays nothing because the call is never answered, and it works on any phone, including feature phones without mobile data.
- The caller's number tells you who called, not which channels they agreed to: say clearly what they will receive, and on which app.
- A WhatsApp reply to a missed call is business-initiated, so it must be an approved template, charged per delivered message.
- Click-to-chat opens a customer-started WhatsApp chat instead, but needs WhatsApp and data; a missed call reaches everyone else.
Chapter 3 · How it unfolds
How does a missed call service work?
Publish the number with the promise
Print or broadcast the number with exactly what the caller will get, for example "Give a missed call to get the price list on WhatsApp". That wording is your opt-in record.
The call rings and is rejected
The platform receives the incoming call, rejects it after a ring or two so it is never answered, and the caller is not charged.
Capture the caller's number
The platform logs the caller's number, the number dialled (useful for telling ads apart) and a timestamp, and posts them to your webhook.
Send the follow-up
Trigger an SMS from your DLT header and template, or a WhatsApp template if the opt-in wording covered WhatsApp. Throttle repeat callers so one person is not messaged five times.
Record consent and route the lead
Store the opt-in with the number, wording, source and time, then push the lead to a CRM or agent queue for a callback.
Chapter 4 · Why it matters
Why does a missed call service matter?
For audiences who would never type a URL or a keyword, one call is the lowest-effort response a business can ask for, and the number alone is enough to follow up. That makes missed calls a strong bridge from offline media into digital channels — as long as the follow-up is what the caller expected, consent is recorded and the system can absorb thousands of calls in the minutes after a TV or radio spot.
Chapter 5 · The facts
A missed call service: key facts and limits
| Cost to the caller | None: the call is rejected before it is answered |
|---|---|
| Works on | Any phone, including feature phones without data |
| Data captured | Caller's number, number dialled, time |
| SMS follow-up (India) | DLT header plus registered content template |
| WhatsApp follow-up | Approved template, charged per delivered message |
| Typical uses | Lead capture, balance enquiry, opt-in, contests |
Chapter 6 · In code
A missed call service in code
// Missed-call webhook (field names vary by provider) → WhatsApp templateapp.post("/missed-call", express.json(), async (req, res) => {res.sendStatus(200); // acknowledge immediatelyconst caller = toE164(req.body.caller); // "+919812345678"const source = req.body.dialled_number; // which ad or posterif (await sentRecently(caller, "24h")) return; // throttle repeat callersawait recordConsent({ caller, source, wording: CAMPAIGN_WORDING, at: new Date() });await fetch(`https://graph.facebook.com/v26.0/${PHONE_NUMBER_ID}/messages`, {method: "POST",headers: { Authorization: `Bearer ${ACCESS_TOKEN}`, "Content-Type": "application/json" },body: JSON.stringify({messaging_product: "whatsapp",to: caller.slice(1), // digits only: 919812345678type: "template",template: { name: "neet_timetable", language: { code: "en" } },}),});});
Acknowledge, de-duplicate, record consent, then send an approved template — the caller has not messaged you, so free-form text is not allowed.
Chapter 7 · Where it goes wrong
Common mistakes with a missed call service
Promising one channel, replying on another
If the poster says "get details by SMS", a WhatsApp marketing template is not what the caller agreed to. Word the call to action for the channel you will use, and keep that wording on record.
Treating caller ID as strong verification
Caller ID can be spoofed on some routes, so a missed call suits low-risk enquiries but should not be the only check before money moves or an account changes.
No throttling of repeat calls
Eager callers ring three or four times. Without de-duplication each call fires a paid SMS or WhatsApp message and irritates the person.
Sizing for the average, not the spike
TV and radio spots produce thousands of calls in minutes. Queue the webhook work and send at a controlled rate rather than calling messaging APIs inline.
Chapter 8 · What good teams do
Best practices for a missed call service
- Use a different number per ad, newspaper or city to measure which placement works.
- Reply within a minute — the caller is often still holding the phone.
- Fall back from WhatsApp to SMS automatically when a number is not on WhatsApp.
- Add a "Call me back" button to the reply for leads that need a conversation.
Chapter 9 · Missed Call Service FAQs