Test Engineer – Core Network Testing

About the Role

Testfyra is looking for an experienced Test Engineer to join our telecom consulting team. As a Testfyra Consultant, you will support leading telecom operators and vendors by validating and assuring Core Network services across virtualized telecom environments.

You will work on complex Core Network testing projects involving subscriber management, voice services, mobility, charging, and network integrations while collaborating with cross-functional engineering teams across the UK and Europe.

Applicants must already have the legal right to work in the UK or Europe. The role may require travel or temporary relocation depending on client project requirements.

Experience Required

• 3–5 years of experience in Telecom Core Network Testing.
• Hands-on experience working with Core Network elements such as SDM, CNDB, IMS and related Core components within virtualized environments.
• Experience working with telecom operators, network vendors, or telecom consulting organisations.
• Strong understanding of mobile Core Network architecture and subscriber management. Key Responsibilities
• Validate subscriber provisioning, registration, authentication, and service profile management across Core Network elements.
• Perform end-to-end validation of voice and IP-based services, including VoLTE, VoWiFi, SMS over IP, emergency services, and supplementary services.
• Execute subscriber registration, attach, deregistration, and SIP signalling validation while ensuring accurate subscriber profile assignment.
• Validate mobility scenarios, including SRVCC, LTE/5G to Wi-Fi handovers, and seamless service continuity.
• Verify subscriber provisioning, policy enforcement, and service trigger configurations.
• Test integrations between Core Network elements and platforms including SDM, CNDB, HSS/UDR, PCRF/PCF, SBC, OCS, MGCF, MSC-S, OSS/BSS, CRM, billing, and provisioning systems.
• Perform regression testing following software upgrades, patches, and new software releases.
• Validate CDR/EDR generation for voice, video, messaging, roaming, and supplementary services.
• Verify prepaid and postpaid charging, policy enforcement, and online charging functionality.
• Conduct performance, stress, load, failover, and high-availability testing across Core Network environments.
• Monitor and analyse latency, call setup times, throughput, signalling behaviour, and overall system performance.
• Develop and maintain automated test suites to improve testing efficiency, scalability, and repeatability.
• Log, track, and prioritise defects using JIRA or equivalent defect management tools.
• Collaborate with developers, Core Network engineers, operations teams, and client stakeholders to investigate and resolve issues.
• Produce clear test reports, KPIs, and recommendations for continuous improvement.

Technical Skills
Core Network

• Strong understanding of Core Network architecture and subscriber management.
• Hands-on experience with Core elements including SDM, CNDB, IMS, HSS/UDR, SBC, PCRF/PCF, OCS, MGCF, MSC-S, and related network components operating in virtualized environments.
• Good understanding of VoLTE, VoWiFi, SRVCC, emergency services, roaming, and 5G Core integration.
• Knowledge of charging and policy control mechanisms.
• Protocols & Networking
• SIP
• Diameter (Cx, Sh, Ro, Rx, Gx)
• RTP/RTCP
• DNS
• ENUM
• Strong understanding of the OSI Model and network troubleshooting methodologies.
• Testing & Analysis Tools

Experience with one or more of:

• Wireshark
• sngrep
• SIPp
• Spirent
• Keysight IxLoad (or equivalent)
• Python
• Robot Framework Test & Defect Management
• JIRA or equivalent defect tracking tools.
• TestRail or similar test management tools would be an advantage but are not essential. Additional Skills
• SQL and CDR/EDR validation.
• ElasticSearch or similar log analysis tools.
• Strong experience analysing packet captures, signalling traces, and network traffic.
• Understanding of OSS/BSS integrations, including CRM, Billing, and Provisioning.
• Awareness of telecom security and lawful intercept requirements. What We're Looking For
• Strong analytical and troubleshooting skills.
• Excellent communication and stakeholder management abilities.
• Ability to work independently and collaboratively within international project teams.
• Comfortable working in customer-facing consulting engagements.
• A proactive mindset with a passion for quality engineering and telecom technologies.

Eligibility

• Must be based in the UK or Europe.
• Must have the legal right to work in the UK or Europe.
• Willingness to travel or temporarily relocate for client assignments when required.

Why Join Testfyra?

At Testfyra, you'll work alongside leading telecom operators and technology vendors on next-generation Core Network projects. We offer exposure to innovative technologies, international consulting opportunities, and an environment where your expertise directly contributes to delivering high-quality solutions for our clients.