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

Base Salary Range The expected base salary range for this role is: $123,900 - $298,800 a year United States (All other areas not listed above): USD $123,900 - $249,000   United States (NYC, CT, NJ, Seattle, LA, San Diego): USD $136,300 - $273,900   United States (San Francisco / Bay Area): USD $148,700 - $298,800   Our salary ranges are determined by role, level, and location. Within the range, individual pay is determined by job-related skills, experience, and relevant education or training.  Our goal is to offer a competitive package that reflects the impact and expertise you bring to the team.  This posting is for a current, active vacancy. More about TextNow  Our culture  We’re proud of the culture that we’ve built at TextNow, but one of the most common questions we hear is ‘how do you continue to sustain it as the world and the company continues to change?’ The reality is that we’re only able to keep up because each and every TextNovian contributes to our culture through being involved, by living our values, sharing feedback, embracing change and more!   Our values  Customer Obsessed  We strive to have a deep understanding of our customers.  Do Right By Our People  We treat each other with fairness, respect, and integrity.  Accept the Challenge  We adopt a "Yes, We Can" mindset to achieve ambitious goals.  Act Like an Owner  We treat this company like it's our own... because it is!  Give a Damn  We are deeply committed and passionate about our work and achieving results.  Our benefits and more  This is a brief overview of the benefits that TextNow offers its employees. More complete details can be found in TextNow’s Benefit Guide and legal plan documents, which are available to employees on or shortly after their start date with TextNow. The benefits listed herein are for illustrative purposes only and may change from time-to-time in TextNow’s sole discretion.  Free phone service  Strong work life blend   Employee stock options   Unlimited vacation   12 paid holidays per year  Competitive pay  Health, dental, and vision benefits  Short-term & long-term disability  $750 annual wellness benefit or healthcare spending account  401(K) matching    Parental leave for eligible employees  Learning & Development opportunities We travel a few times a year for various team events, company-wide off-sites, and more  More information about our total rewards package will be available during the hiring process.  Dogfooding & Customer Obsession  At TextNow, every employee gets to actively use our app for calling and texting. Dogfooding helps us experience what customers do, to spot issues early, and drive better design, developer, and user experiences.  Diversity and Inclusion  Our aim is to make every person who joins TextNow feel like they belong, that they’re valued, and that they’re able to be their authentic selves at work.   We’re all accountable for creating an inclusive culture and a sense of belonging for one another. By doing this together, we’ll make TextNow better for everyone.   Equal opportunity  We are an equal opportunity employer and are committed to creating an inclusive environment for all employees. We consider all qualified applicants without regard to race, color, religion, sex, gender identity or expression, sexual orientation, age, disability, or any other protected characteristic.  Applicants who require reasonable accommodation during the hiring process may contact our Talent Team.  AI usage: We use artificial intelligence (AI) tools to support parts of the hiring process, such as reviewing applications, analyzing resumes, or assessing responses. These tools assist our recruitment team but do not replace human judgment. Final hiring decisions are ultimately made by humans. If you would like more information about how your data is processed, please contact our Talent Team. TextNow Candidate Policy  By submitting an application to TextNow, you agree to the collection, use, and disclosure of your personal information in accordance with the TextNow Candidate Policy