HLR / HSS / UDM Architect

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 (e.g., Ericsson HLR, Nokia FlexiISN, Huawei HLR9820) and their MAP/TCAP/SCCP signaling stacks.

Hands-on experience with HSS platforms and Diameter-based interfaces: S6a, S6d, Cx, Sh, Zh — including Diameter routing agent (DRA) configuration and troubleshooting.

Practical experience with 5G UDM and UDR, including cloud-native deployments (containerized/Kubernetes-based NFs) and HTTP/2 SBI interfaces (N8, Nudm_SubscriberDataManagement, Nudr_DataRepository).

Solid understanding of subscriber profile structures: EPS subscription data, 5GS subscription, IMS subscription (Cx/Sh), CAMEL service data, and operator-determined barring.

Experience with IMSI/MSISDN range management, number portability (NP/MNP) integration, and SIM/eSIM provisioning workflows.

Strong knowledge of SS7 stack: MAP (Mobile Application Part), TCAP, SCCP, MTP — including MAP operations for location update, authentication, subscriber info retrieval, and SMS routing.

Diameter protocol expertise: peer configuration, routing, AVP manipulation, error handling, and Diameter watchdog/transport management.

Familiarity with 3GPP standards governing subscriber data: TS 23.008, TS 29.272 (S6a), TS 29.328/29.329 (Sh), TS 29.503/29.504 (UDM/UDR SBI), TS 23.502 (5G procedures).

Understanding of roaming architecture, IR.21 data, IREG testing, and GSMA interconnect requirements relevant to subscriber data exchange.

Working knowledge of 2G (HLR/AuC/VLR), 3G (HSS/HLR), 4G (MME/HSS/EPC), and 5G SA (AMF/SMF/UDM/UDR/AUSF/UDSF) core architectures and their subscriber data flows.

Comfortable with Linux/Unix-based systems — able to navigate shells, interpret logs, manage processes, and perform basic system administration on telecom NF hosts.

Hands-on with Wireshark, tcpdump, and vendor-specific trace tools for deep analysis of MAP, Diameter, and HTTP/2 subscriber signaling.

Experience with high-availability configurations for subscriber databases: active/standby, geo-redundancy, and database replication/synchronization.

2+ years of scripting experience (Python, Bash) for automation of provisioning, audit, and reconciliation tasks on HLR/HSS/UDM/UDR systems.

Experience with AUSF, UDSF, or PCF in 5G SA environments.

Familiarity with cloud-native telecom platforms (OpenShift, Kubernetes) and Helm-based NF lifecycle management.

Exposure to OSS/BSS integration for subscriber data, including provisioning APIs and mediation layer design.

Knowledge of eSIM (GSMA SGP.02 / SGP.22) and its interaction with subscriber data repositories.

Experience with MVNO/MVNE operating models and multi-tenant subscriber data isolation.

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