Senior Core Network Engineer (HLR/HSS & SDM)

As our Senior HLR/HSS Specialist, you are the guardian of our subscriber data and the architect of our roaming efficiency. You won't just manage databases; you will own the life-cycle of HSS/HLR templates that allow our MVNO to scale globally. Your expertise in Profile & Template Engineering is critical to our success in maximising COGS and margin through sophisticated Steering of Roaming (SoR) and Sponsor Roaming integrations.

Your main responsibilities will be:

• Design and maintain HLR/HSS subscriber templates, ensuring precise configuration of roaming profiles, APN/PDN contexts, and Camel/Diameter triggers.
• Collaborate with roaming partners to implement and refine SoR logic within the HLR/HSS, ensuring subscribers attach to preferred networks based on cost and quality.
• Lead the technical deployment of Full MVNO profiles, managing specific QoS profiles and addressing (GTs, APNs) required for independent network operations.
• Act as the primary technical point of contact for our System Integrators, auditing HLR/HSS configurations, reviewing change requests, and ensuring alignment with the 2026 roadmap.
• Define and monitor critical HLR/HSS KPIs, including Location Update (LU) success rates and Diameter Transaction per Second (TPS) limits.

What you’ll need:

• Deep technical mastery of MAP (SS7) and Diameter (S6a/S13) protocols; additional experience with VoLTE Roaming (S8HR) or SMSoIP rollout is a significant advantage.
• Subscriber Mapping: Extensive experience with HLR, HSS, and UDM (User Data Management) in a multi-tenant or MVNO/E environment.
• Practical experience with Multi-IMSI applets and the logic required to manage roaming through Sponsor IMSIs.
• A solid understanding of GSMA IREG (IR series); familiarity with TADIG (TD series) and how HSS/HLR templates impact billing/settlement is preferred.
• A "detective" mindset for troubleshooting complex signalling failures using tools like Wireshark or roaming-specific platforms (e.g., Mobileum, Roamware, or SIGOS).
• Proven ability to manage technical projects with external System Integrators and roaming partners under tight deadlines.

Bonus Points

• Experience with 5G Unified Data Management (UDM) and Authentication Server Functions (AUSF).
• Knowledge of Cloud Native Network Functions (CNF) and containerised core deployments.
• Scripting skills (Python/Bash) for automating provisioning audits or log parsing.