Job Title: Voice Core Engineer (IMS/CS)
Location: Lisbon, Portugal (2 days per week in office, 3 days from home)
Experience Required: 3+ year
Language Requirement: Portuguese & English (fluent)
Role Overview
We are seeking a skilled Voice Core Engineer with at least 3 years of experience working in IMS and CS Voice Core networks. The ideal candidate will be well-versed in VoLTE architecture, voice call flows, and telecom network behaviour. This role is ideal for an engineer with strong technical knowledge, excellent communication skills, and a proactive, collaborative mindset.
Key Responsibilities
* Operate and maintain IMS/VoLTE and CS core network components.
* Work with key IMS/VoLTE network nodes: SBC, x-CSCF, TAS (MMTel-AS, SCC-AS, IP-SM-GW, IM-SSF), BGCF, MGCF, MRF.
* Manage CS core elements: MGW, MSC, IM-MGW.
* Analyze and troubleshoot VoLTE call flows (e.g., VoLTE-VoLTE, T-ADS, homing, break-in/out).
* Understand and evaluate subscriber profile parameters in HSS/HLR and their impact on service delivery.
* Work confidently with key VoLTE protocols: SIP, Diameter, DNS, H.248, CAMEL, RTP/RTCP.
* Apply knowledge of VoLTE/VoWiFi architecture and operational concepts.
Preferred Experience
* Exposure to HSS, HLR, CuDB environments.
* Familiarity with signaling transfer elements such as DRA, STP.
* Knowledge of DNS/ENUM and Number Portability (NP) processes.
* Hands-on experience with equipment from major vendors: Huawei, Oracle, Ericsson, Mavenir, Nokia.
Qualifications
* Bachelor's or Master's degree in Electronics, Telecommunications, or Computer Engineering.
* Professional certifications from Ericsson, Huawei, Nokia, or Cisco are a strong plus.
* Proven customer-facing experience within telecom operators or service providers.
Soft Skills
* Strong verbal and written communication skills in Portuguese and English.
* Excellent organizational and prioritization abilities.
* A collaborative team player with a proactive and hands-on approach.