App Overview

WhatCall icon

WhatCall

Innovative Developers LTD · Utilities

Simply dial with WhatCall and the person you dial will receive an instant missed call from your number, while you are directed straight to their voicemail without ringing and any possibility of them answering your call.

$1.99 · In-app purchases

PRICE
$1.99
In-app purchases
BUSINESS MODEL
Paid
No overall Grossing estimate available
RATING
4.2
598 ratings · Top 30%

Evidence scope: No current overall US chart position is available. Category-chart positions shown in discovery are a separate scope. Revenue is a directional model estimate, not verified earnings.

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Build Kit

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A product spec, screen plans, and build steps for your coding agent.

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Combine features and design from your favorite apps.

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What's included18 files

A product spec, phased build plan, differentiation notes, and screen references.

  • START_HERE
  • AGENTS
  • EVIDENCE
  • SPEC
  • BUILD_PLAN
  • DIFFERENTIATION
  • skills/
  • screens/
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Illustrative example: an invoice app for independent contractors. Your kit is tailored to the app you choose; this is not its generated content.

Feature spec

Goal: Send a clear invoice after finishing a job.

  • Add a client, line items, a due date, and payment instructions.
  • Preview the total before exporting a PDF.
  • Keep an editable draft if export fails.

Screen plan

Invoice editor: Client at the top, editable line items in the middle, total and preview action at the bottom.

States: Empty draft, validation errors beside each field, exporting, and a retry action that preserves the draft.

Differentiate and validate

Hypothesis: Contractors need faster repeat invoices more than more templates.

First experiment: Test duplicating a previous job with five contractors. Watch where they hesitate before expanding the feature set.

The full kit adds a phased build plan, evidence notes, tool prompts, and implementation guidance. It is a plan for your coding agent, not a finished app.

Usage: Mechanics are fair game; never reuse the original name, branding, assets, or verbatim copy.

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Quick prompt

> SELECT BUILD PLATFORM:

Good fit for mobile-first iOS and Android prototypes with managed app scaffolding.

// RORK SYSTEM PROMPT
Rork plan preview for WhatCall: map the core Utilities workflow, choose the smallest differentiated feature set, define the data and monetization boundaries, then prototype the riskiest user journey first.
            

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Opportunities

AI-GENERATED OPPORTUNITY HYPOTHESES

These are generated suggestions, not verified review quotations. Check current App Store reviews and speak with users before treating a possible gap as a requirement.

Hypothesis 1

Integrate a more comprehensive database for caller ID.

Assumption to check: Limited caller identification for unknown numbers

Validate with people who use this workflow before building.

Hypothesis 2

Ensure a uniform design language throughout the app.

Assumption to check: Inconsistent user interface across screens

Validate with people who use this workflow before building.

Hypothesis 3

Provide users with customizable settings for notifications and themes.

Assumption to check: Lack of customization options for users

Validate with people who use this workflow before building.

Hypothesis 4

Clarify subscription tiers and their benefits within the app.

Assumption to check: In-app purchase confusion

Validate with people who use this workflow before building.

App evidence

Original App Store material. Ratings and screenshots describe the existing app, not proof of demand for your version.

App Store description

Simply dial with WhatCall and the person you dial will receive an instant missed call from your number, while you are directed straight to their voicemail without ringing and any possibility of them answering your call. WhatCall helps you avoid returning or making a call when you don't really want to speak to someone, but gives you the excuse and proof that you tried! With WhatCall they'll even receive a missed call text message from their network if it supports that feature! WhatCall works in every country and on most networks that have a voicemail including landline and mobile. It automatically figures out all the dialling codes so you can go ahead and dial in the same local format you use on your iPhone (See screenshot examples for US, UK and Japan). Examples of where WhatCall is useful: - Calling in sick to work but don't want to speak to your boss and answer lots of awkward questions. With WhatCall your boss with think you tried calling them while you can leave a voicemail letting them know you won't be in to work. - Returning a call to a friend or partner when you're busy and don't have time to speak to them. WhatCall will connect you straight to voicemail allowing you to leave a message without spending precious time getting drawn into a conversation. - Leaving a message for someone you know is unable to answer the phone (eg. in a meeting or putting a baby to sleep) but may have forgotten to turn off their phone. WhatCall will direct your phone calls to their voicemail without ringing and disturbing them. - Leaving an important message for someone when you don't have time for a full conversation or to type out a long SMS message, use WhatCall and dial direct to voicemail instead.

Written user reviews are not shown here. Check current App Store reviews >

Screenshots

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Build scope

Plan a focused first version with your coding agent. These are planning assumptions, not a delivery guarantee.

Define the first version

Choose one audience and one core workflow. Use the kit to agree on its screens, data, and acceptance criteria before building.

Set boundaries

Decide which secondary features, integrations, and platform support can wait. Your version does not need to reproduce everything in the original.

Check the hard parts

Validate external services, specialist technology, data access, and ongoing costs for your chosen scope.

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BUILD KIT DIFFICULTY
Advanced

From the Build Kit assessment.

A reliable timeline needs an agreed scope and a technical check. Ask your agent to estimate the phases in BUILD_PLAN.md after that review.