Mobile Core Engineer, Carrier

TextNow is a full MVNO. We run our own converged 4G/5G mobile core in AWS for hundreds of thousands of subscribers, growing toward millions, and we're growing the team that owns and evolves it. AI is built into how this team works: it's how a small team operates, triages and changes a network this size.

About the role

You've run a mobile core at a carrier and want to do it on a cloud-native platform. You'll be the person on the team who knows what the network is supposed to do: how an attach should flow, why a Diameter or SIP request failed, what a policy rule does to a subscriber's traffic.

You'll work alongside our SRE, who owns the cloud platform, and developers who build the services around the core.

Where you'll work: remote anywhere in the US or Canada, with working hours that overlap Eastern time. You'll travel to our Waterloo office a few times a year to work in the device lab and meet the team, so you need to be able to travel to Canada.

What you'll do

• Operate our converged 4G/5G core: packet core, IMS, HSS/UDM and related network functions.
• Define what we monitor: the alarms, KPIs and thresholds that matter, wired into paging with SRE.
• Own config changes: change plans, rollback criteria and impact analysis, shipped through the change pipeline our SRE runs.
• Validate vendor software in our lab before it reaches production.
• Own capacity and SIMs: subscriber, session and license headroom, SIM management and over-the-air (OTA) updates.
• Lead partner and device onboarding: devices (UE), roaming partners and SIM profiles. You'll learn the parts that are new to you and lead the area.
• Lead core incidents: protocol, charging and policy issues. Read the capture, find the cause.
• Lead voice interconnect and roaming signalling: SBCs and SIP trunks, Diameter routing and IPX, and signalling security, so fraud and spoofed signalling get caught early. You'll learn the parts that are new to you.
• Keep lawful intercept working with the team, with checks so changes don't break it.
• Work with our vendor on defects, bringing evidence to every escalation and pushing for root causes that hold up.
• Teach the automation what good looks like. Turn your network knowledge into runbooks, health checks and investigation steps that AI agents can follow. Lead on core alarm correlation, config change auditing and unusual call or data session patterns.
• Bring the team up to speed. The SRE and developers all ramp up on the core and share on-call for it with you. You set the direction for the core, and the team shares the load.
• Use AI across the job: triaging alarms, reading logs and captures, digging through vendor docs, drafting change plans.

Who you are

• 5+ years operating a live mobile core in production for an operator (carrier, MVNO or MVNE). Vendor experience counts if you were on call for a customer's live network
• Hands-on EPC/5GC packet core (PGW, SMF, UPF); working knowledge of IMS
• Working knowledge of policy and charging (PCRF/PCF, OCS, quota enforcement)
• Comfortable reading and dissecting a packet capture end to end
• You've written and run MOPs, upgrades and maintenance windows in production
• You've led production incidents
• Comfortable deciding what "correct" looks like when nobody else knows
• You don't settle for how things have always been done. You look for better ways to run the network, even when "that's how carriers do it" is the easy answer
• You already use AI to triage, analyze logs and captures, and automate the repetitive parts of operations

Nice to have

• Alarm correlation or noise reduction on vendor network function alarms, or automated runbooks for core operations
• Cloud-native network functions on Kubernetes
• DPI-based traffic classification
• Onboarding and troubleshooting devices (UE)
• Working with GSMA roaming specs (IR.21, IR.88)
• Python or Go, git, kubectl