HLR / HSS / UDM Architect

You will analyze, design, implement, and verify the configuration and integration of subscriber data management nodes, networks, and systems across 2G through 5G infrastructure. Your scope of work includes introduction, upgrade, expansion, functionality, and capacity scenarios spanning legacy HLR environments through modern cloud-native UDM and UDR deployments. You will be a key contributor to the convergence of subscriber databases as the MVNO platform evolves toward 5G standalone architecture, directly shaping the reliability and scalability of the networks partners depend on. You will own the subscriber data management platform across network generations, manage provisioning workflows, monitor node KPIs, own incident management, perform maintenance and security audits, and participate in a 7x24 on-call rotation.

Responsibilities

• Manage and operate HLR, HSS, UDR, and UDM nodes across 2G, 3G, 4G, and 5G core domains, ensuring high availability and data integrity for subscriber profiles
• Design and maintain subscriber provisioning workflows, including IMSI/MSISDN management, service profiles, and roaming configurations
• Implement and verify MAP, Diameter (S6a, S6d, Cx, Sh, Zh), and HTTP/2-based (N8, Nudm) interfaces connecting subscriber data nodes to MSC, MME, AMF, SGSN, and other core elements
• Use and build dashboards to monitor subscriber node KPIs and identify patterns before they become outages
• Own incident management for the subscriber data domain, following internal escalation and external vendor coordination procedures to meet SLAs
• Perform maintenance, security audits, patching, and emergency response for HLR/HSS/UDM/UDR platforms
• Undertake fault handling and corrective actions at node, service, and infrastructure level, including protocol trace analysis on Diameter, MAP, and HTTP/2 signaling
• Lead and contribute to project activities including E2E introduction of new subscriber management nodes, capacity expansions, software upgrades, and feature activations
• Support MVNO onboarding by configuring subscriber data repositories, IMSI ranges, and roaming agreements
• Participate in 7x24 on-call rotation including shift monitoring and emergency response
• Provide, implement, and verify improvements to processes and work instructions and drive automation of repetitive provisioning and audit tasks
• Collaborate with IMS, RAN, and transport teams to resolve cross-domain subscriber authentication and registration issues

Requirements

• At least 10 years of experience in core network engineering with a focus on subscriber data management in mobile networks
• BSc degree in Telecommunications, Computer Science, or equivalent; post-graduate studies are a plus
• 10+ years of core telecommunications network experience, with a minimum of 5 years hands-on with HLR, HSS, UDR, or UDM platforms
• Deep operational knowledge of HLR platforms and their MAP/TCAP/SCCP signaling stacks
• Hands-on experience with HSS platforms and Diameter-based interfaces: S6a, S6d, Cx, Sh, Zh, including DRA configuration and troubleshooting
• Practical experience with 5G UDM and UDR, including cloud-native deployments and HTTP/2 SBI interfaces
• Solid understanding of subscriber profile structures
• Experience with IMSI/MSISDN range management, number portability integration, and SIM/eSIM provisioning workflows
• Strong knowledge of SS7 stack: MAP, TCAP, SCCP, MTP
• Diameter protocol expertise including peer configuration, routing, AVP manipulation, error handling
• Familiarity with 3GPP standards governing subscriber data
• Understanding of roaming architecture, IR.21 data, IREG testing, and GSMA interconnect requirements
• Working knowledge of 2G, 3G, 4G, and 5G SA core architectures and their subscriber data flows
• Comfortable with Linux/Unix-based systems
• Hands-on with Wireshark, tcpdump, and vendor-specific trace tools
• Experience with high-availability configurations for subscriber databases
• Strong written and verbal communication skills in English
• Able to work under pressure during high-severity incidents
• Ready to work on morning/afternoon shifts and participate in on-call rotation