AND Digital telecom provider API exercise which exposes 3 endpoints:

1. Get all phone numbers of all customers (GET)
2. Get all phone numbers of a customer (GET)
3. Activate a phone number for a customer (PUT)

Implemented with Spring Boot and builds with Gradle.

-3 layers (controller, service and repository) -uses a dummy repository (a real database not required) -basic exception handling (area for improvement) for missing resources -test cases implemented for controller and service layers