Senior Network Engineer (F/M)

We are looking for an expert engineer to lead the design, deployment, and expansion of our Packet Switched (PS) Core Network. This is a hands-on role that bridges the gap between high-level network architecture and low-level protocol analysis. You will take ownership of the core network evolution, supporting legacy 3G, dominant 4G LTE, and emerging 5G NSA architectures. You will work closely with vendors to define requirements, validate solutions, and ensure a seamless rollout and operation of critical network functions.

Your main responsibilities will be:

Design and dimension the Packet Core (EPC/5GC) to ensure scalability for data growth.

Manage roaming coverage with IPX/GRX providers, roaming sponsors, and direct bi-lateral agreements.

Define specific network profiles and configurations for HSS/UDM subscribers, including QoS, AMBR, and APN subscriptions.

Architect the DNS hierarchy for the mobile core, focusing on S-NAPTR records for MME/SGSN to discover PGW/SGW/UPF nodes.

Plan and implement IP routing strategies, including ASN (Autonomous System Number) management and BGP peering for internet and roaming connectivity.

Manage Access Point Name configurations for various service types, including IMS, Internet, and IoT.

Perform deep-dive troubleshooting of signaling procedures across 3G (Iu-PS), 4G (S1-MME, S11, S5/S8), and 5G NSA (EN-DC).

Apply in-depth understanding of 3GPP standards for 3G, 4G EPC, and 5G NSA mobile data call-flows.

Analyze and optimize critical flows, specifically Attach/Registration (Authentication vectors, ULR/ULA, Create Session) and Bearer Management (Dedicated bearer creation for VoLTE/QCI 1 and default bearers).

Utilize protocol analyzers such as Wireshark or Tektronix to decode ASN.1 based messages and Diameter signaling (Gx, Gy, S6a, S5, S8, GTP-C, GTP-U).

Act as the primary technical interface with core network vendors, system integrators, and partners.

Lead technical evaluations and design reviews for core network expansions.

Manage the ATP (Acceptance Testing) phase to ensure vendor deliveries meet operational standards prior to live deployment.

Does this sound like you?

Experience with a Tier 1 Carrier, Mobile-Operator, or Major Network Equipment Provider (NEP) background.

Deep understanding of SGSN, GGSN, and HLR architecture.

Extensive experience with PGW, HSS, SGW, and MME.

Proficiency in 5G Non-Standalone (NSA), 5G Standalone (SA), and PCC.

Hands-on experience with Diameter S6a (HSS-MME), Gx (PCRF-PGW), and Gy (OCS-PGW).

Strong knowledge of IP addressing, subnetting, OSPF/BGP routing, VRFs, and ASN management.

Expert-level DNS resolution (A, AAAA, SRV, NAPTR), DHCP, and IPX/GRX management.

Bonus Points

Experience managing inbound/outbound roaming via Sponsor IMSI providers.

Technical knowledge of GTP-Proxy deployments for signaling and payload optimization.

Practical experience working within an MVNO or MVNE environment.

Familiarity with Regional and Local Breakout (LBO) strategies to reduce latency.

Experience with Cloud Native Network Functions (CNF) and containerized core deployments.