A group of small services combine to deliver user specific service.

The statement accurately describes a microservices architecture, which is a foundational principle of the 5G Service-Based Architecture (SBA) covered in the NOKIA BL0 220 curriculum. In this model, a large application or system is decomposed into a collection of smaller, loosely coupled, and independently deployable services. These services communicate with each other, typically via APIs, to perform complex functions and deliver a complete, user-specific service. The 5G Core Network Functions (e.g., AMF, SMF, UPF) are implemented as cloud-native microservices that collaborate to provide end-to-end connectivity and services for users.

B. False: This is incorrect. The statement is the defining characteristic of a microservices or service-based architecture, a valid and fundamental model for modern cloud-native systems, including the 5G core.

1. 3GPP TS 23.501 V16.7.0 (2020-12), "System architecture for the 5G System (5GS); Stage 2," Section 4.2.3, Service-based architecture. The standard states, "The 5G System architecture is defined as a service-based architecture. ... A Network Function (e.g. AMF) can expose its functionality as a service. This service can be 'consumed' by other authorized Network Functions." This confirms that multiple services (NFs) combine to deliver functionality.

2. Nokia White Paper (2020), "The 5G core: A cloud-native core for a 5G world," Page 4. The document explains, "The 5G Core (5G-C) is based on a Service-Based Architecture (SBA) in which the control plane functionality and common data repositories are delivered by way of a set of interconnected Network Functions (NFs), each with authorization to access each other’s services." This directly supports the concept of small services combining to deliver a larger service.