How MissCall works

You might expect a complex description — but the principle is simple. MissCall runs quietly in the background of your Android phone, watches incoming calls, and when one is missed, sends an SMS from your number based on rules you defined. Here is what happens behind the scenes, step by step.

Step 1: You install and sign in

After first launch, you create an account (email + password) or sign into an existing one. MissCall downloads your templates and rules from the cloud and stores them in memory. From this moment everything works offline too — the app does not need a data connection to operate (only to sync settings).

During installation the app requests three key Android permissions: read phone state (to know about incoming calls), send SMS (to be able to reply), and start at boot (to keep working after restart). Nothing else. It does not read your contacts, does not track location, does not read other SMS.

Step 2: Phone detects a missed call

Android sends a system broadcast with information about an ended call. MissCall captures only those marked "missed" — i.e. unanswered. Calls you actively rejected with the reject button can be optionally ignored (caller knows you are online).

Detection works on all modern Android versions (8.0+) and all manufacturer flavors. Tested on Samsung, Xiaomi, Pixel, Huawei, Honor, OnePlus.

Step 3: App picks the right template

From your rules, the app selects a template that matches the current situation:

1. Whitelist / blacklist? — If the number is on the blacklist, no SMS is sent. If on whitelist, proceed to step 2.
2. Manual status — If you have a manual status enabled (e.g. "I'm in a meeting"), its template is used.
3. Schedule — If no manual status, the app looks at the weekly schedule and finds the active template for this time and day.
4. Default template — If nothing matches, the generic "universal" message is used.

Variables are filled in if present. For example {time} becomes the current time, {return_date} the return date from vacation, {caller_name} the name from your contact list (if calling from a known number).

Step 4: SMS goes from your SIM

The app passes the prepared message to the Android SMS API. The message is sent from your primary SIM card (with dual SIM, you can choose a specific one in settings). Caller receives the SMS typically within 2 seconds of call end — often before they can call again.

SMS counts toward your operator limit, just as if you had typed it manually. If you have an unlimited SMS tariff, you pay nothing. MissCall itself does not charge for sending — the subscription covers app operation, not SMS itself.

Step 5: Logged to history

Every sent SMS is saved in app history and synced to the web. You can see retrospectively who called when, which template the app used, and whether the message was actually sent. If an error occurred (insufficient credit, etc.), the log will show it.

What if I have no signal or data?

SMS itself does not need data — it goes through the regular GSM network. If you have no signal at all, MissCall queues the message and sends it as soon as signal returns. Settings sync with the web requires internet, but the rules themselves work offline (from local cache).

What about battery?

The app runs only when a call comes in — no constant running, no GPS tracking, no keep-alive. Battery consumption is so small that built-in Android statistics often do not even register it. Tested on devices in 24-hour use — difference vs. a phone without MissCall is in the order of tenths of a percent per day.