Core Network Engineer (5G)
Company: Limitless Mobile
Location: Richardson
Posted on: April 2, 2026
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Job Description:
Position: Core Network Engineer (5G) Location: Richardson, Texas
Reporting to: Director of Engineering Role: The Core Network
Engineer (5G) works within the Engineering department and is
responsible for the design, deployment, operation, and optimization
of Limitless Mobile's 5G core network platforms. The role is
focused on hands-on engineering execution, supporting both internal
network operations and contracted wholesale customer deployments
across U.S. and international environments. Innovation is delivered
through practical improvements in automation, reliability,
observability, and deployment efficiency rather than strategic
product ownership. Tasks/Responsibilities: Core Network Design,
Deployment and Management Design, deploy, operate, and maintain 5G
Core Network (5GC) components including AMF, SMF, UPF, NRF, PCF,
AUSF, and UDM across both SA and NSA deployments. Deploy, manage
and operate 5G core environments in high-availability and
geo-redundant configurations, ensuring resilience, scalability, and
service continuity. Support inter-PLMN connectivity including
roaming, SEPP, and secure interconnect architectures. Support
mediation requirements for billing / charging and performance
statistics on 5G core platform. Perform end-to-end call-flow
debugging and protocol-level troubleshooting across N1, N2, N3, N4,
N6, N10, N11, and N12 interfaces. Implement and support network
slicing, policy control, and service function chaining. Ensure
compliance with relevant 3GPP specifications, security
requirements, and interface protocols (e.g. HTTP/2, PFCP, SCTP).
Collaborate with RAN and infrastructure teams to support lab
test-cells, and limited production radio deployments where
required. Integrate, harden, and operate both vendor-supplied and
open-source 5G core solutions (e.g. Open5GS, free5GC, Magma) in
test, pre-production, and production environments. Contribute
fixes, enhancements, and operational tooling where appropriate to
support production stability and maintainability. Use automation to
reduce mean time to repair (MTTR), improve deployment
repeatability, and increase operational visibility. Develop and
maintain custom scripts and tooling (e.g. Python, Bash, Go) to
automate deployment, configuration, testing, monitoring, and fault
analysis. Pre-Sales Provide technical input and peer review to
pre-sales and solution architecture activities, validating
feasibility, integration complexity, and operational impact.
Contribute implementation-level considerations and constraints to
High-Level Design (HLD) documentation produced by Solution
Architects. Projects Execute assigned technical workstreams within
contracted wholesale customer projects, including deployment,
integration, testing, and handover to operations. Work under the
direction of the Director of Engineering and in coordination with
Solution Architects and Project Manager to deliver agreed technical
outcomes. Operations Provide Tier-3 technical support to the
Network Operations Centre (NOC) for live network incidents
affecting wholesale and internal services. Participate in
escalation and support on-call rotations as required. Conduct
root-cause analysis, document findings, and implement corrective
and preventative actions. Skills Development Continuously develop
technical expertise across core network functions, infrastructure
platforms, and emerging 3GPP features relevant to Limitless
Mobile's network roadmap. Measurement: Performance will be assessed
based on a combination of delivery effectiveness, operational
stability, incident resolution time, change success rate, and
successful deployment of wholesale customer solutions. Desired
Expertise & Experience: Bachelor's or Master's degree in computer
science or engineering. Minimum of 5-8 years working in the
telecommunications industry designing, integrating and managing
mobile core network propositions for e.g. a Network Equipment
Provider or carrier / Mobile Network Operator (MNO). Deep
understanding of 5G Core architecture (SA/NSA), 3GPP specs, and
control/user plane functions. Experience with open source 5G cores
like Open5GS, free5GC, or Magma. Experience with Mongo database for
opensource 5G solutions is a plus. Programming in at least one of
the C++, Python, Golang, Bash, or equivalent languages. Familiarity
with containerization (Docker, Kubernetes), Git, and CI/CD tools.
Hands-on experience with Wireshark, PCAP analysis, and log-level
debugging. Minimum of five years of systems integration, management
and/or technical support of 4G / LTE and 5G mobile core network
components. In-depth knowledge of mobile voice and data core
network architecture (including MNO and MVNO / MVNE infrastructure
architecture) as well as network topology, including ability to
describe the key elements of a mobile network and understand how
the components function and interact as well as how mobile calls
are made and received and how mobile data sessions work both in
VoLTE and VoNR environments. Understanding of Packet Switched
network elements, interfaces and messaging for 4G / LTE networks,
including IMS architectures and PCRF. Understanding of Voice SIP /
RTP, ISUP and voice convergence technologies, including IMS
(including VoLTE and VoWiFi). Understanding of RADIUS and Diameter
for both signaling and charging scenarios. Experience of capacity
management and dimensioning of mobile core elements. Familiarity
with LI (Lawful Intercept), E911 and CALEA requirements.
Familiarity with IMS and VoNR architecture. Demonstrated experience
implementing and operationalizing technically robust mobile core
network solutions aligned with customer, regulatory, and
operational requirements. Desired Personality: Entrepreneurial and
proactive and accountable self-starter, comfortable with taking
ownership of complex technical problems and hunger to make a
difference as well as strong performance and results orientation.
Ability to thrive in a fast-paced start-up environment, managing
multiple projects and deadlines in parallel with ability to
recognise and adjust priorities as required. Detail-oriented,
methodical, and well organised yet able to demonstrate a high
degree of flexibility and adaptability. Able to operate calmly and
methodically in live-network and incident-driven environments.
Ability to work effectively both independently as well as in a
team. Effective communicator with strong documentation discipline
and the ability to collaborate across engineering and operations
teams. Positive and constructive personality, including willingness
to go beyond the call-of-duty to ensure successful and on-time
delivery of the projects. Residence Requirement: Candidate must
have authorization to work in the US.
Keywords: Limitless Mobile, Rowlett , Core Network Engineer (5G), IT / Software / Systems , Richardson, Texas
