Senior Core Network Engineer (HLR/HSS & SDM)

At Airalo, we make it easier for people to stay connected wherever they travel. As the world's first eSIM store, we help millions of travelers access mobile data in over 200 countries and regions.

We’re a fully remote team of 400+ people across 60+ countries, building a product used at a global scale every day. Work here is structured but fast-moving, with clear ownership and the space to make decisions without unnecessary layers.

For many people joining us from the UK, it’s the combination that stands out: transparency, meaningful autonomy, and the ability to do high impact work without in office constraints.

• Location: Remote, anywhere in the UK.
• Contract: Full-time, permanent.
• Benefits: Learn more about our benefits here in this link - https://airalo-public.notion.site/Benefits-25396a97ffca81fb9bc1f0be479f1be3?pvs=74 
• Languages: English is our main working language day to day, so you'll need to be comfortable communicating in it both in meetings and async.

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.

We started Airalo to make staying connected effortless, wherever you are in the world. Today, millions of travelers rely on our eSIMs, and many of the people building the product first discovered us as customers.

Our team spans 60+ countries, but what people often notice quickly is how work actually feels here. There’s trust to own what you do, space to focus without constant layers of process, and a clear sense of what you’re responsible for from day one.

As Airalo continues to grow, people tend to stay for a mix of things: the chance to work on a product used globally, the autonomy to shape how they work, and the opportunity to keep taking on new challenges without getting stuck in one lane.