Mobile Core Engineer (Remote)
Telnyx
| Company | Telnyx |
| Category | Engineering |
| Location | Dublin; Amsterdam; Krakow |
| Remote | Remote |
| Employment | Not stated |
| Level | Not stated |
| Salary | Not stated by the employer |
| Posted | 26 Feb 2024 |
| Last verified | 3 Aug 2026 |
| Source | Employer career page (greenhouse) |
Description
About Telnyx
Telnyx is an industry leader that's not just imagining the future of global connectivity—we're building it. From architecting and amplifying the reach of a private, global, multi-cloud IP network , to bringing hyperlocal edge technology right to your fingertips through intuitive APIs, we're shaping a new era of seamless interconnection between people, devices, and applications.
We're driven by a desire to transform and modernize what's antiquated, automate the manual, and solve real-world problems through innovative connectivity solutions. As a testament to our success, we're proud to stand as a financially stable and profitable company. Our robust profitability allows us not only to invest in pioneering technologies but also to foster an environment of continuous learning and growth for our team.
Our collective vision is a world where borderless connectivity fuels limitless innovation. By joining us, you can be part of laying the foundations for this interconnected future. We're currently seeking passionate individuals who are excited about the opportunity to contribute to an industry-shaping company while growing their own skills and careers. About you
You'll be part of the Core Wireless Squad — an 11-person team responsible for running and improving Telnyx's wireless EPC infrastructure.
We operate a mobile core spread across multiple data centres with several roaming partners and a range of vendor platforms.
The opportunity
This is a hands-on operations role. You'll spend your time debugging real subscriber issues, working pcap traces, coordinating with roaming partners and vendors, and keeping the mobile core healthy. The work is deep protocol-level investigation combined with practical platform operations.
The Role
Subscriber & connectivity troubleshooting
Investigate end-to-end attachment failures across S6a (Diameter), MAP (SS7), GTP-C, and GTP-U
Decode pcap traces from DRA, STP, and GTP proxy capture points to isolate signalling failures
Trace individual IMSIs across protocols and partner networks to find where sessions break
Diagnose DNN/APN routing mismatches, IMSI-pinned APN gaps, and private wireless gateway configuration issues
Handle customer-reported SIM connectivity issues end-to-end — from initial report through root cause to fix
EPC platform operations
Manage and troubleshoot HSS/HLR, DRAs (freeDiameter with custom Python transforms), STPs, PGWs, SMFs, and GTP proxies (Go)
Work with etcd-based steering/blocking infrastructure (forbidden PLMNs, platform-level blocking, 3G blocking)
Operate the GTP proxy routing database (IMSI groups, IMSI-pinned APNs, cache invalidation)
Participate in vendor management — escalating and driving resolution with platform vendors and roaming partner NOCs
Roaming & interconnect
Support sponsored roaming relationships and direct bilateral agreements
Investigate roaming registration failures, NRTRDE gaps, and steering/blocking issues
Coordinate with partner NOCs on S6a/MAP/GTP incidents, including pcap exchange and joint root-cause analysis
On-call & incident response
Participate in the weekly on-call rotation (1 week on, 10 weeks off)
Respond to Opsgenie alerts — SMF overload, DRA peer down, HSS failures, GTP session rejects, charging errors
Drive incident resolution end-to-end, coordinating across internal teams and external vendors
Write post-incident summaries and feed learnings back into tooling and runbooks
Automation & tooling
Use and extend our pcap analysis tooling and protocol decoders to speed up investigations
Contribute configuration and automation for EPC infrastructure (Ansible, Kubernetes)
Improve observability — Grafana dashboards, alerting rules, protocol-level metrics
Where a fix or diagnostic needs a small code change, be comfortable making one — but this is an operations role, not a
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