About the role

We are building a cloud-native, high-scale 4G/5G converged packet core for NB & NR over satellite (NTN). We're hiring Core Engineers to design, build, and run the cloud-native services this core is made of from the data structures and concurrency model inside a single network function, up through how that service behaves under real production load on Kubernetes. This isn't a role split between "the person who writes the code" and "the person who runs it." You own both ends of that lifecycle for the services you build.

What you`ll do

- Design and implement core network functions (AMF, SMF, UDM, MME, and peers) as stateless, cloud-native services with correct use of data structures, concurrency, and OS-level primitives at the core of the implementation, not just the API surface.

- Build services for real distributed-systems failure modes: partial failures, retries, race conditions across replicas sharing state through Valkey/MemoryDB via compare-and-swap, and network partitions in a multi-AZ EKS deployment.

- Take a service from design through implementation, deployment, and production support including writing the Helm charts and CI/CD path it ships through, not handing that off to someone else.

- Instrument what you build with structured logs, OpenTelemetry metrics, and health checks from day one, so when it breaks in production, you can tell why from the dashboard before you touch a terminal.





- Carry production support for the services you own you're in the loop when they page, not just when they ship.

Required Skills

- Deep, hands-on understanding of core computer science fundamentals, including algorithms and data structures, operating systems, distributed systems theory, networking, and concurrent/parallel programmingnot merely familiarity with frameworks that abstract these concepts away.

- Proven experience designing, implementing, and operating highly scalable cloud services from the ground up, at a scale of tens of thousands of transactions per second and tens to hundreds of millions of tracked entities (such as subscribers, sessions, or equivalent), rather than services scaled to only a few thousand users.

- Experience working in a DevOps model on cloud-native, high-uptime services, with accountability for uptime as well as feature delivery.

- Experience designing reliable systems for massive concurrent loads, with the ability to reason concretely about target metrics such as sustained throughput, concurrent connections, and failure budgets rather than aiming for as much as possible.”

- Full software lifecycle ownership, with equal comfort handling production incidents and participating in design reviews.

- Bonus: Experience with 3GPP protocols (NAS, S1AP, NGAP, Diameter), Kubernetes-based network functions, or telecom core networks.

📌 Core Engineer - Cloud Native (4G/5G Core) (Bengaluru)
🏢 Calsoft
📍 Bengaluru