The job involves participating in a project to modernize T-Mobile's key systems using modern technologies such as microservices and containers. You will be involved in the design of technologies and the target architecture, driving this transformation. Responsibilities include upgrading applications from Oracle Java to a higher version of OpenJDK, preparing applications for microservices and their operation in a Kubernetes cluster, migrating application servers from JBoss to WildFly, collaborating on the transition from Oracle DB to PostgreSQL, and ensuring security using SAML and OAuth2.