Mobile Core Design Specialist – Gateway & Services

About the role

Our team defines customer‑facing mobile data services and the platforms that deliver them, such as SGW, PGW, SMF, UPF, DNS, Gi‑LAN and CGNAT. As a Mobile Core Design Specialist you will lead the design of one or more of these services for brands like EE and BT, shaping the experience of millions of users on the UK’s best‑performing network.

Key responsibilities

• Author high‑level and low‑level design documents, configuration guides and sequence flow diagrams.
• Provide backup coverage for at least one other service or platform to avoid single points of failure.
• Liaise with vendors and suppliers to integrate solutions.
• Analyse logs and packet traces to diagnose issues and drive improvements.
• Measure capacity and traffic profiles to ensure network performance meets customer demand.
• Offer ad‑hoc consultancy to other teams based on specialist knowledge of mobile core services.
• Participate in project meetings, design reviews and post‑implementation reviews.

Required profile

• Strong desire and ability to understand complex technical systems and translate them into optimal designs.
• Excellent written communication skills, able to produce clear documentation for varied audiences.
• Proficiency in creating technical diagrams, flow charts and timelines.
• Hands‑on experience with Juniper and Cisco routing platforms in large‑scale environments.

Required skills

• Juniper routing platforms
• Cisco routing platforms
• Log analysis and packet‑trace troubleshooting
• Capacity planning and traffic profiling
• Network design documentation (high‑level and low‑level)
• Familiarity with SGW, PGW, DNS, Gi‑LAN and CGNAT technologies
• Vendor liaison and integration

What we offer

• Competitive salary with great benefits
• Opportunity to work on a cloud‑native 5G core using container orchestration
• Impactful role influencing the experience of millions of mobile customers