PHP/Laravel Developer Needed: Migrate Customized Invoice Ninja v4 to Current Version

We need an experienced PHP/Laravel developer to migrate a customized production Invoice Ninja v4 installation to a current supported version. This is not a standard upgrade. Our Invoice Ninja installation contains custom functionality used to bill our telephony/VoIP customers. The existing system processes telephony billing/usage data and uses it for automated customer invoicing. The developer will need to: analyze the existing Invoice Ninja v4 installation identify custom modifications understand and document the current billing workflow create a safe migration strategy migrate our Invoice Ninja data to the current version port/reimplement the custom telephony billing functions create a staging environment test old vs. new billing results migrate the tested solution into production Required skills: PHP Laravel MySQL/MariaDB Linux legacy PHP application migration API/integration development Git/code comparison Invoice Ninja experience is highly preferred. Experience with VoIP, CDR or usage-based billing is a plus. When applying, please describe your previous Invoice Ninja experience and how you would approach identifying and migrating custom modifications from Invoice Ninja v4. We want to start with a paid analysis phase before agreeing on the complete migration.