Ericsson Ericsson Travelping Deutsche Telekom AG Telecom Italia Ericsson BISDN The introduction of network and service functionality virtualization in carrier-grade networks promises improved operations in terms of flexibility, efficiency, and manageability. In current practice, virtualization is controlled through orchestrator entities that expose programmable interfaces according to the underlying resource types. Typically this means the adoption of, on the one hand, established data center compute/storage and, on the other, network control APIs which were originally developed in isolation. Arguably, the possibility for innovation highly depends on the capabilities and openness of the aforementioned interfaces. This document introduces in simple terms the problems arising when one follows this approach and motivates the need for a high level of programmability beyond policy and service descriptions. This document also summarizes the challenges related to orchestration programming in this unified cloud and carrier network production environment. A subsequent problem is the resource orchestration. This is handled separately in [I-D.caszpe-nfvrg-orchestration-challenges] and will be merged in the next iteration of this document.