A daily list on your phone, so many checks need no internet
Realcaller downloads a list of up to 10,000 numbers for your region every day. When a call comes in, the phone looks there before it asks the server anything.
What is the offline list?
A saved list of numbers that people have complained about in your region, stored on your phone and refreshed once a day.
It holds up to 10,000 numbers. On the United States list was about 73 KB compressed, so it is a small download.
Besides the full list, the phone fetches small daily updates. Entries that have not been refreshed or seen for 30 days are removed, so the list does not fill with stale numbers.
Which region does my phone get?
The region of your SIM card. With no SIM, the phone asks for the US list.
- How the region is found
- From the SIM country that Android reports. No location permission, and never GPS.
- What the sync sends
- The region code and the time of your last sync. No phone number and no device ID.
- What a Mexican SIM gets today
- There is no Mexican seed data yet, so the list holds the top US numbers, and Mexico will grow from user reports. Mexico and the app.
Why does an offline list make checks faster?
Because answering from the phone skips the network, and the network is the slow part.
Your own lists first
Contacts, blocklist and allowed list are checked on the phone.
Recent answers, then the offline list
The phone looks in its short memory of recent answers, then in the offline list stored on the phone.
The server is the fallback
Only when neither has the number does the app make a live request, over HTTPS.
On a call, the app’s own time budget for a live answer is 600 ms. The server request is capped at 550 ms and the whole decision at 580 ms. If nothing arrives in time the card says “not checked”. That 600 ms is the app’s own design limit, not a deadline set by your phone. There is no field data yet on real-world speed or on how often the offline list answers.
What can I control?
Three things in Settings, under “Data updates”.
- Wi-Fi only
- Off by default, which means background updates use any network. Turn it on to download only over Wi-Fi.
- Update now
- Checks for the latest data straight away. It ignores “Wi-Fi only”.
- Last updated
- Shows when the list last refreshed, for example “11 minutes ago”.
What is in the list?
Today, US government complaint data, plus numbers that several app users reported once the app is in use.
- Complaint data
- Numbers from FTC and FCC complaints. As of , the database has 813,371 US numbers, and the phone keeps up to 10,000 of them. Our data.
- Community numbers
- A number reported from 2 or more phones in 90 days goes into every phone’s offline list, up to 2,000 of them.
- Spam activity in your region
- The Protection tab shows the 10 highest-scoring numbers from your offline list.
What are the limits of an offline list?
It is a snapshot, so it can miss new numbers and read slightly differently from a live check.
- A number that is not in the list needs the live lookup. Without internet the card says it was not checked.
- The offline score leaves out the region part of the score, so one number can read “Suspicious” on a live lookup and “Low risk” from the offline list.
- Explanations about region (“Source data is from US; your region is MX”) show only on live lookups, never for numbers answered from the list.
- The list is region-wide, not personal. It does not learn who calls you.
Offline protection questions
Does the app work with no signal?
How big is the download?
Can I limit updates to Wi-Fi?
Why is the list limited to 10,000 numbers?
Keep reading
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