Cirrus Core Networks
Senior Core Network Engineer
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About CCN
Cirrus Core Networks is a US-based telecom core network operator and managed services provider serving MVNOs and MNOs.
Role Summary
The Senior Core Network Engineer is CCN's final technical escalation point for critical incidents across the mobile core. The role leads core network deployments from planning through handover, as well as root cause analysis, complex troubleshooting, performance tuning, and migration execution. It also serves as the senior technical bridge to CCN's distributed NOC and Operations teams.
Technology Scope
- 5G SA core: AMF, SMF, UPF, UDM, UDR, AUSF, PCF, NRF, NSSF, NEF, SEPP, BSF, CHF, N3IWF
- 4G EPC: MME, SGW, PGW, HSS, PCRF, DRA/DEA
- IMS and voice: P-CSCF, I-CSCF, S-CSCF, TAS, MRF, BGCF, MGCF, VoLTE, VoWiFi
- Non-3GPP access: ePDG
- Roaming and interconnect: GTP Proxy, DEA, SEPP, IPX/GRX, Diameter–MAP interworking
- Legacy 2G/3G: HLR/AuC, MSC/VLR, SGSN, GGSN, STP, EIR, CAMEL
- Messaging and charging: SMSC, SMSF, OCS/OFCS
- Protocols: Diameter, GTP-C/GTP-U, SIP, SS7/SIGTRAN, MAP, HTTP/2-based SBI, PFCP
Key Responsibilities
- Escalation & Incident Leadership
- Serve as final technical escalation point for Sev-1 and critical outages across the technology scope above.
- Lead root cause analysis and drive corrective actions to closure.
- Troubleshoot complex multi-vendor, multi-protocol issues, including cross-generation interworking and roaming failures.
- Deployment Leadership & Operations
- Lead core network deployments end to end, including planning, implementation, testing, cutover, and handover to operations, in line with approved architecture.
- Coordinate vendors, internal teams, and customer technical contacts throughout deployment.
- Lead platform migrations and cutovers.
- Own performance tuning and capacity monitoring for production platforms.
- Produce low-level designs and implementation plans.
- Vendor Validation
- Plan and run vendor solution validation and acceptance testing, in coordination with the Senior Core Network Architect and Product Management.
- Manage technical escalations with vendors through to resolution.
- Team Enablement
- Mentor NOC engineers and raise escalation capability across CCN's distributed operations teams.
- Develop and maintain troubleshooting runbooks and operational documentation.
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Required Qualifications
- 7+ years of hands-on mobile core operations or engineering in a production environment
- Proven experience leading mobile core deployments or migrations in a production operator or managed services environment
- Direct experience leading Sev-1 incident resolution and formal root cause analysis
- Hands-on experience operating 4G EPC and IMS functions, including HSS, PCRF, DRA, and packet core
- Working knowledge of legacy 2G/3G core networks (HLR, MSC/VLR, SGSN/GGSN, SS7/MAP) and troubleshooting across network generations
- Strong troubleshooting across Diameter, GTP, SIP, and SS7/SIGTRAN, including protocol trace analysis
- Experience operating virtualized or containerized network functions
- Clear, calm communication during high-pressure incidents with internal teams, customers, and vendor
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Preferred Qualifications
- 5G SA core exposure, including service-based interface troubleshooting
- Experience operating GTP Proxy, ePDG, or roaming interconnect platforms
- Experience working with distributed, multi-region NOC and Operations teams
- Experience in a managed services or MVNO/MNO operator environment
To apply
Send your resume to: careers@cirruscorenetworks.com
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