Core PS / IP Engineer

Location: Chisinau, Moldova Responsible for the operation, maintenance, troubleshooting and optimization of Mobile Core PS and IP infrastructure, including legacy EPC and next-generation virtualized and cloud-based Core platforms. The role contributes to the introduction, integration and evolution of NFVI, 5G NSA/SA and 5G Core technologies, as well as to the interworking of PS, CS and IMS domains, ensuring the reliable operation of end-to-end mobile services. Key Responsibilities: 1. Core PS & IP Network Operations Operate, monitor and maintain Core PS network elements and related IP infrastructure, including virtualized/NFVI platforms. Monitor network availability, performance, capacity and key operational KPIs. Identify potential performance and capacity issues and contribute to network optimization. 2. Troubleshooting & Network Analysis Troubleshoot issues related to mobile data, APN, session establishment, mobility, authentication, DNS and IP connectivity. Analyze GTP, Diameter and IP traffic using packet captures, logs and network monitoring tools. Investigate and resolve IP connectivity and routing issues, including BGP, VLAN, VRF, NAT and ACL related problems. Perform root-cause analysis and provide effective solutions for service-impacting incidents. 3. 5G, NFVI & Network Transformation Support the introduction, integration and stabilization of 5G NSA/SA and next-generation Core technologies. Participate in NFVI deployments, migrations, software upgrades and network modernization projects. Support the evolution towards virtualized and cloud-native Core environments. Contribute to testing, integration and troubleshooting during network transformation projects. 4. Roaming & Interworking Support roaming services and troubleshoot issues in cooperation with internal teams and roaming partners. Support troubleshooting of PS/CS/IMS interworking issues related to VoLTE, voice, SMS and other IMS-based services. 5. Technical Collaboration Work closely with internal technical teams, vendors and technology partners to investigate and resolve complex network issues. Participate in incident resolution, technical investigations and network improvement initiatives. Contribute to technical documentation and knowledge sharing within the team. Required Knowledge & Experience: Bachelor's degree in Telecommunications, IT, Computer Science or a related field. 3–5 years of relevant experience in Mobile Core, Packet Core and/or IP networks. Solid understanding of LTE/EPC architecture and good knowledge of 5G NSA/SA concepts. Good knowledge of GTP-C/GTP-U, Diameter, TCP/IP and DNS. Good understanding of IPv4/IPv6, routing, BGP, VLAN, VRF, NAT and ACL. Practical experience with Wireshark/Tshark, packet capture analysis, network monitoring and log analysis. Good knowledge of Linux/Unix CLI. Understanding of NFVI, virtualization and cloud-based/cloud-native Core environments. Basic understanding of CS Core and IMS/VoLTE service flows, including voice and SMS interworking. Good technical English and the ability to communicate effectively with vendors and internal technical teams. Will Be an Advantage: Experience with Ericsson, Huawei or other Mobile Core solutions. Practical experience with NFVI, 5G Core, virtualized network functions and/or cloud-native platforms. Knowledge of CS Core, VAS and IMS/VoLTE, including voice, SMS, USSD and signaling flows. Experience with Diameter-based services related to IMS/VoLTE. Knowledge of Kubernetes and/or OpenStack. Basic Python and/or Bash scripting skills. Experience with network migrations, upgrades and technology transformation projects. Key Competencies: Strong analytical and troubleshooting skills. Systematic and structured approach to problem solving. Strong sense of ownership and accountability. Ability to work effectively under pressure, especially during service-impacting incidents. Teamwork and cross-functional collaboration. Clear and effective technical communication. Ability to learn and adapt to new technologies. Proactive approach to network optimization and continuous improvement.