Senior Engineer, Core Network in London

About Airalo

Airalo is the world's first eSIM store that helps people connect in over 200+ countries and regions across the globe. We are building the next digital service that revolutionises the telecom industry. We are a travel-tech company and an equal-opportunity environment that values and executes diversity, inclusion, and equity. Our team is spread across 50+ countries and six continents. What glues us together is our commitment to changing the way you connect.

About you

We hope that you care deeply about the quality of your work, the intrinsic worth of tasks, and the success of your team. You are self-disciplined and do not require micromanagement in terms of your skillset and work ethic. You do your best to flourish as an individual every day while working hard to foster a collaborative team environment. You believe in the importance of being — and staying — authentic, honest, positive, and kind. You are a good interlocutor with clear and concise communication. You are able to manage multiple projects, have an analytical mind, pay keen attention to detail, and love to get your hands dirty. You are cognizant, tolerant, and welcoming of vulnerabilities and cultural differences.

About the Role

Position: Full-time / Employee
Location: Remote-first
Benefits: Health Insurance, work-from-anywhere stipend, annual wellness & learning credits, annual all-expenses-paid company retreat in a gorgeous destination & other benefits

As our Senior Core Network Engineer, you aren’t just maintaining servers; you are the architect of a borderless world. You will own the evolution of our global Packet Core, ensuring a traveller in Tokyo has the same seamless 5G experience as someone in London. If you enjoy the 'detective work' of deep-dive signalling analysis and the 'architect work' of building scalable 5G systems, this is your next challenge.

Your main responsibilities:

• You’ll lead the design and growth of our Packet Core (EPC/5GC), ensuring our network scales effortlessly as our global traveller base doubles and triples.
• You’ll be our primary architect for global connectivity, managing roaming coverage through IPX/GRX providers and securing bi-lateral agreements that keep our users online everywhere.
• You’ll dive deep into signalling procedures across 3G, 4G, and 5G NSA. When a connection fails, you’re the expert who decodes the "why" using tools like Wireshark to look under the hood of Diameter and GTP signalling.
• You’ll fine-tune critical network flows—from the moment a user "attaches" to the network to the creation of high-quality voice and data bearers—ensuring every byte is delivered with precision.
• You’ll lead design reviews and manage the "Acceptance Testing" (ATP) phase to ensure our partners deliver to the high standards our users expect.

Does this sound like you?

• You’ve spent significant time in the "engine room" of a Tier 1 Carrier, Mobile Operator, or a major Equipment Provider. You understand the stakes of a live, global network.
• You are fluent in the language of mobile networks. Whether it’s legacy 3G (SGSN/GGSN), dominant 4G (MME/PGW), or the transition to 5G, you understand how these systems interlock.
• You have a rock-solid grasp of IP networking—BGP routing, subnets, and ASN management are second nature to you.
• You understand that "it’s always DNS." You have hands-on experience architecting the DNS hierarchy (S-NAPTR) that allows mobile nodes to discover one another across the globe.

Bonus Points:

• You have practical experience working within the unique constraints and opportunities of an MVNO or MVNE environment.
• You are excited about the future of telco and have experimented with or deployed Cloud Native Network Functions (CNF) and containerised cores.
• You’ve worked with Local Breakout (LBO) strategies to ensure data takes the fastest path possible to the internet.
• You have a niche understanding of managing roaming through Sponsor IMSIs to expand coverage quickly and efficiently.

If you are interested in this position, please apply via the link.

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.

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.