Senior Core Network Engineer (HLR/HSS & SDM)

Location: Europe; United Kingdom Workplace: remote Help Us Build The Future of Travel At Airalo, we're making it easier for people to stay connected wherever they travel. As the world's first eSIM store, we help millions of travelers access affordable mobile data in 200+ countries and regions around the world. Today, we're a team of 400+ people across 60+ countries, building a product used by travelers every day. We've grown quickly, but we've worked hard to keep what matters: trust, ownership, and the freedom for people to do great work without unnecessary layers or bureaucracy. We're fully remote by design, genuinely global, and united by a shared mission to make travel simpler for everyone. Your Next Destination Location: Remote. 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.   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. If you are interested in this position, please apply via the link. Why People Join Us 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 were customers first. Our team spans 60+ countries, united by a shared belief that great work happens when people are trusted to own what they do. 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, so do the opportunities to learn, take on new challenges, and make a real impact - from anywhere in the world. Before You Hit Apply By applying, you acknowledge and agree that, in case of successful application, Airalo may request to run background checks as a condition for entering into an agreement with you. Rest assured that these checks will only occur upon your prior consent and at the end of the selection process, and will be strictly limited to what is allowed under the laws that are applicable to you. All data that you share or that we collect in connection with such checks will be processed in accordance with our Privacy Policy, available here: www.airalo.com/more-info/privacy-policy?srsltid=AfmBOooBT0rXAj1FaNelZ3VfN0wvhwzvAoxdtHnOKSVETpiSjiXVuycy    We sincerely thank all applicants in advance for submitting their interest in this opportunity. Airalo is an equal-opportunity employer and values diversity, equity & inclusion. We do not discriminate on the basis of race, religion, national origin, gender, sexual orientation, age, marital status, veteran status, or disability status. We are committed to providing reasonable accommodations upon request for individuals with disabilities throughout our job interview process. At Airalo, we believe in roaming-free recruitment. Just as we provide clear connectivity for travelers, we provide clear salary ranges for our candidates. 🌍 This role is remote and open to candidates across our supported locations in Europe. The range below reflects the full salary range for this role across the countries where it's available: 📍 UK: £75000 – £110000 📍 Ireland: €64,800 – €93,150 📍 Western/Northern Europe (Germany, France, Austria): €54,800 – €152,950 📍 Southern Europe (Spain, Portugal, Italy, Greece): €44,000 – €96,600 📍 Central & Eastern Europe (Czechia, Hungary): €52,296 – €101,568 📍 South-Eastern Europe / Balkans (Romania, Serbia, Bulgaria): €50,000 – €103,235 Your Home Destination: 🛫 Local market rates and cost of living vary. Your specific range within this band depends on where you're based. We'll walk through your range together on your first call with our Talent team so we're aligned for takeoff! 🎒✨