The IMS Core Test Engineer will be responsible for the end-to-end testing and validation of our IP Multimedia Subsystem (IMS) network elements and services. This role involves designing test strategies, developing and executing test cases, analysing results, and troubleshooting complex issues to ensure network stability, performance, and feature functionality. The ideal candidate is a detail-oriented problem-solver with a deep understanding of IMS architecture and VoIP protocols.

Key Responsibilities

• Test Planning & Strategy: Develop detailed test plans, test cases, and test strategies for new IMS features, network integrations, software upgrades, and regression testing.
• Test Execution: Perform rigorous functional, integration, system, regression, and performance testing on IMS core network elements (e.g., CSCF, MGCF, MGW, BGCF, TAS, SBC, HSS).
• Protocol Analysis: Utilize protocol analyzers (e.g., Wireshark) to capture and analyze SIP, DIAMETER, RTP, and HTTP/2 messages to identify and diagnose call flow and service-related issues.
• Lab Environment Management: Configure and maintain the IMS test lab environment, including provisioning test subscribers and simulating network conditions.
• Defect Management: Log, track, and manage defects with precise detail using tools like JIRA. Work closely with development and design teams to troubleshoot, replicate, and verify fixes.
• Automation: Develop and maintain automated test scripts using tools and programming languages (e.g., Python, Robot Framework, SIPp) to improve testing efficiency and coverage. (nice to have)
• Documentation: Create and maintain clear and concise technical documentation, including test reports, test summaries, and method of procedure (MOP) documents.
• Collaboration: Work collaboratively with cross-functional teams including R&D, Product Management, Network Planning, and Operations to ensure quality standards are met throughout the product lifecycle.

Required Qualifications & Skills

• Bachelor’s degree in Telecommunications, Electrical Engineering, Computer Science, or a related field.
• 3+ years of hands-on experience in testing and validating IMS core networks in a telecom environment.
• In-depth knowledge of IMS architecture, protocols, and call flows (SIP, DIAMETER, RTP, DNS, ENUM).
• Strong experience with IMS network elements and their functions: P/I/S-CSCF, TAS/MTAS, SBC, MGCF, MGW, BGCF, HSS.
• Proven expertise in using protocol analysis tools like Wireshark, (or Tektronix, Astellia, etc.) for troubleshooting.
• Hands-on experience with test simulators and traffic generators (e.g., SIPp, Landslide, Spirent, Ixia).
• Solid understanding of LTE/5G network architecture and how it interworks with IMS for VoLTE.
• Experience in creating and executing detailed test plans and test cases.
• Strong analytical and problem-solving skills with a meticulous attention to detail.
• Excellent verbal and written communication skills.

Preferred Qualifications

• Experience with performance and load testing of IMS nodes.
• Programming/scripting skills for test automation (e.g., Python, Bash, Perl, Robot Framework).
• Experience with virtualised and cloud-native network functions (VNF/CNF) and related technologies (Kubernetes, Docker, OpenStack).
• Knowledge of VoWiFi (eVoWiFi) and eCall specifications.
• Familiarity with 3GPP and GSMA standards and specifications related to IMS.
• Experience working in an Agile/Scrum development environment.