CallShield is a crowdsourced mobile app that identifies and auto-blocks spam calls by aggregating user ratings. Everyone who joins helps grow the 3.2M-entry number database.
"Unknown callers, unstoppable spam, no reward for reporting" — a story of building a brand-new platform from scratch in six months, in-house, satisfying the three pillars of reassurance, participation, and continuity all at once.
TelecomGuard is on a mission to protect people from the rising tide of specialized fraud and spam calls. It chose a participatory approach — aggregating nuisance-number data that no individual or single company could gather alone, as ratings from each and every user.
At the core of the business model is a virtuous cycle: the more users rate numbers, the more the database grows, and that accuracy in turn draws more users. Posts earn points redeemable for coupons, sustaining the community's ongoing participation.
Submit a rating as Harmful / Spam / Useful.
Merge ratings and update identification data.
Updates the CallKit / device directory.
Show the caller, block spam numbers. Reward posters with points.
None of these were technology-selection issues — they were business requirements tied directly to reassurance, participation, continuity, and accuracy. Building new from scratch, we had to design them so all four hold at once.
Get the mechanism wrong, and spam-number info stays scattered across individuals, unused — so identification accuracy never improves.
Without instant caller info, users can't tell whether to answer, suffering harm and lost opportunities.
Design no reward for reporting, and reporting becomes a dead letter, so the database never grows.
Get the sync design wrong, and the latest ratings never reach the device, so blocking doesn't work.
We built the four pillars — reassurance, participation, continuity, and accuracy — from scratch, in-house. The design runs end to end: a data platform aggregating user ratings, instant display on the OS-native incoming-call screen, point rewards that sustain participation, and automatic sync to devices.
This foundation isn't a technology metric — it keeps producing business outcomes: lower fraud-exposure risk, peace of mind for families, and a database that grows itself.
Shows the risk level on incoming calls so users can judge safely.
Auto-blocks dangerous numbers, so elderly family members can use their phones with peace of mind.
More participation means higher accuracy, which in turn attracts more users.
Delegates information gathering to the community, minimizing operational load.