What are the three service provider business models?

Outsourced 3rd party and off-shore party are not recognized ITIL service provider classifications - ITIL uses the terms Internal, External, and Shared Service Unit.

Internal and external service operations provider are not the correct ITIL terms - the proper designations are Internal Service Provider, External Service Provider, and Shared Service Unit.

Outsourced 3rd party is not a defined ITIL provider type - the correct third model is the Shared Service Unit (Type II), which is internally owned but shared across business units.

ITIL recognizes Type I (Internal Service Provider, embedded within a specific business unit), Type II (Shared Service Unit, serving multiple internal business units from a shared function), and Type III (External Service Provider, serving external customers). These three types cover the full spectrum of sourcing and delivery relationships in ITIL service management.