WebTrit Developer — Fork & Rebrand Open-Source Softphone App (iOS + Android)

Your bid MUST include answers to the 5 questions at the bottom of this posting or it will be immediately rejected.
We're a UK-based eSIM and mobile network company launching a branded international calling service. We need an experienced developer to fork, rebrand, and customise the WebTrit Phone open-source softphone app and get it published to both app stores.
IMPORTANT: Read this entire posting carefully. There are specific questions at the bottom you MUST answer. Generic proposals will be rejected immediately.

What is WebTrit?
WebTrit Phone is a Flutter/Dart softphone app that uses WebRTC for voice and video calling. It connects to SIP-based VoIP systems via a REST API. The full source code is available on GitHub.
What We Need Done
Phase 1 — Fork & Rebrand

Fork the WebTrit Phone repo into our private repository
Rebrand: app name, logo, colours, splash screen, app icons, bundle ID (iOS + Android)
Configure embedded web pages for in-app promo/top-up screens
Connect to our SIP trunk (Telnyx and/or VoIP.ms) for international call termination
Configure push notifications for incoming calls
Build and test on both iOS and Android

Phase 2 — BSS Connector (Authentication & Billing)

Build a custom BSS connector that authenticates users against our WooCommerce customer database via REST API
Implement two-tier access: Free tier vs Subscriber tier (different rates based on customer status)
Display user's calling credit balance within the app
Integrate call billing: deduct credit per call based on tier and destination

Phase 3 — App Store Submission

Prepare store listings, submit to Apple App Store and Google Play
Handle review feedback until both apps are approved and live


Required Experience

Hands-on experience with the WebTrit Phone Flutter app — forking, customising, or deploying it
Strong Flutter/Dart development (iOS + Android)
SIP/VoIP experience — configuring SIP trunks, understanding call flows, WebRTC
Python/FastAPI for the BSS adapter
App store submission (Apple + Google)

Nice to have: Telnyx or VoIP.ms, WooCommerce REST API, Asterisk/FreePBX

Budget & Timeline

Open to proposals (fixed-price per phase )

Ongoing maintenance likely after launch


HOW TO APPLY — YOU MUST ANSWER THESE QUESTIONS
Proposals that don't answer ALL of the following will be deleted without reading. We are specifically looking for WebTrit experience and will verify your answers.
Question 1 — Prove you know the WebTrit repo
Go to the WebTrit Phone GitHub repository. What is the name of the directory that contains the app's main Dart entry point? Don't Google this — if you haven't cloned the repo, you won't know.
Question 2 — BSS connector detail
WebTrit uses a specific architecture to connect to external systems for user authentication. In their example Python BSS adapter on GitHub, what OAS/OpenAPI specification version does the adapter implement, and what is the base path prefix for the API endpoints? (This is in the repo — if you've worked with it, you'll know immediately.)
Question 3 — Show your work
Send a screenshot (not a link, an actual screenshot) of your local development environment with the WebTrit Phone project open — either currently or from a past project. If you haven't worked with WebTrit before but have strong Flutter/VoIP experience, send a screenshot of a VoIP/softphone app you've built running on a device or emulator, AND explain specifically which WebTrit repos you've reviewed and what you found notable about their architecture.
Question 4 — Your specific VoIP experience
Describe one SIP integration challenge you faced in a past project and how you solved it. Be specific — name the SIP provider, the issue (e.g., codec negotiation, NAT traversal, onethat way audio), and your fix. Generic answers like "I have 10 years VoIP experience" tell us nothing.
Question 5 — The filter
Start your proposal with the word "Hadeda" so we know you've read this far. Proposals that start with "Dear Hiring Manager" or "I am excited to apply" will be auto-rejected.

What We DON'T Want

-Copy-paste proposals that don't answer the questions above
-"I can do anything" generalists — we need specific WebTrit/VoIP/Flutter experience
-Agencies bidding on behalf of developers we can't interview directly
-Proposals that re-describe our project back to us (we wrote it, we know what it is)
-AI-generated cover letters — we will check, and you will be blocked