Senior Software Engineer (Telco & Comms)

About Callsign

Key responsibilities

• Write production-ready code and understand the deployment pipeline and chart.
• Produce low-level designs and represent the team in architecture reviews.
• Threat-model features and design authentication, authorization, and data handling from the start.
• Instrument releases, participate in on-call, and drive faults to root cause.
• Identify technical gaps, propose cost-benefit-aware fixes, and use AI tooling.
• Mentor engineers, maintain testing and error-handling standards, and interview candidates.

Requirements

• 8+ years with Java 17+, Spring Boot, and Spring Security; debug JVM and Spring issues using thread dumps, heap dumps, and traces.
• Design and operate client-facing microservices; handle API versioning and unit, integration, contract, and load testing.
• Design for failure and scale with idempotency, retries, circuit breakers, and caching; diagnose bottlenecks using data.
• Model relational data and design queries, primarily in MySQL; tune schemas and indexes under load.
• Apply OWASP Top 10 principles, authentication and authorization, secrets management, and secure data handling.
• Write implementation-ready designs and review peers’ designs.
• Operate services on Kubernetes with Docker, Helm, AWS, and CI/CD; debug failed deployments.
• Own changes from design through on-call and instrument services to surface faults.

Preferred experience

• Reactive Java in production using Spring WebFlux, Project Reactor, RxJava, or Vert.x is a plus.
• MNO and telco integrations, including number insight, SIM swap, and other network signals, are a plus.
• OAuth 2.0, JWT, SAML, FIDO, or WebAuthn experience is a plus.
• Regulated-industry delivery, contractual uptime practices, production Kafka, and Terraform are additional advantages.

Benefits

• Private premium health insurance, visa costs, and a one-month paid hotel stay on arrival.
• Annual home-country airfare allowance, annual leave, and a company bank holiday.
• Paid maternity and paternity leave, competitive salary, and end-of-service gratuity.