IMS / Core Test Engineer - 5G

IMS / Core Test Engineer - 5GLocation: Bristol 3x a week. About the RoleQualitest is seeking an experienced IMS / Core Test Engineer to support the validation and testing of mobile network core and IMS services for a leading telecommunications client. The successful candidate will be responsible for ensuring the quality, performance, and reliability of voice, messaging, data, and next-generation communication services across complex telecom environments.Working closely with network engineering, development, operations, and vendor teams, you will execute end-to-end testing activities across IMS, EPC/5GC, VoLTE, VoWiFi, and related network domains, supporting both new feature delivery and production assurance initiatives.Key ResponsibilitiesDesign, develop, execute, and maintain test cases for IMS and Core Network platforms.Perform end-to-end testing of VoLTE, VoWiFi, SMS, MMS, data services, and supplementary services.Validate IMS call flows, SIP signalling, Diameter interfaces, and network interoperability.Execute functional, integration, regression, system, and user acceptance testing activities.Analyse network traces and logs to identify root causes of defects and performance issues.Support testing across EPC and 5G Core network elements including MME, HSS, PCRF, AMF, SMF, UDM, and PCF.Validate roaming, emergency calling, handover, and mobility management scenarios.Collaborate with vendors and internal stakeholders to investigate and resolve defects.Create detailed test reports, defect documentation, and release readiness assessments.Support automation initiatives where applicable to improve testing efficiency and coverage.Participate in release planning, risk assessment, and production deployment activities.Required Skills & ExperienceExperience working within telecommunications testing environments.Strong understanding of IMS architecture and protocols.Hands-on experience testing VoLTE, VoWiFi, SIP, Diameter, RTP, and related technologies.Knowledge of EPC and/or 5G Core network components and interfaces.Experience using network analysis tools such as Wireshark, QXDM, or similar.Ability to analyse signalling traces and troubleshoot end-to-end service issues.Experience working with defect management and test management tools.Understanding of mobile network architecture including LTE and 5G technologies.Strong analytical, troubleshooting, and communication skills.