Senior VoIP Engineer

About Tin CanTin Can is building a safer, simpler way for kids to connect — without smartphones. We’re creating screen-free, delightful devices and services that let families call the people who matter most, free from the noise of today’s digital world.We’re building a bold, authentic, nostalgic, and kinda quirky brand that resonates with folks who want something simpler & better for their kids than the tech-infused lives we’re currently living (and who have a sense of humor about it). As we gear up to scale to thousands of families, we’re ready to bring on an engineer to help make it happen.The RoleA call either connects or it doesn’t — there’s no partial credit when a kid picks up a Tin Can to reach Grandma, or to dial 911. We’re hiring a Senior VoIP Engineer to own the SIP and media plane that carries every one of those calls: how it routes, how it sounds, and how we know it works. It’s the first role dedicated entirely to that stack.Our production stack is Kamailio (SIP proxy and registrar) and FreeSWITCH (media and voicemail), running on AWS across carrier trunks and our own device fleet. This is a deeply hands-on role: routing logic, dial plans, and packet captures every day. You’ll report to the Head of Engineering and own the call itself. You’ll set the direction for how the voice plane is designed and tuned and when a registration flaps at 3am, you’re the person who can go from a SIP trace to root cause and out the other side with a fix.What You’ll DoOwn our production SIP and media plane end to end — Kamailio, FreeSWITCH, and the carrier trunking behind every call to the outside worldBe the reviewer of record for call-path changes, and author the SIP test scenarios that gate a voice change before it shipsWrite and maintain the Kamailio routing logic behind every call — dispatcher, registrar and usrloc tuning, htable, DMQ replication, TLSBuild FreeSWITCH dialplans and integrations (ESL, mod_xml_curl, Lua, Sofia profiles), and keep call state correct across boxes, transfers, and NATProduce the packet-level truth about call quality — MOS, jitter, packet loss, setup time — and make it trustworthy enough to alarm onModel and load-test call capacity — concurrent calls, calls per second, trunk headroom — against our holiday peak, using scenarios built on real call flowsExtend the SIP and media layer into new countries as we expand, where codec support and emergency-calling rules change market to marketHarden the signaling and media path: SIP over TLS, SRTP, rate limiting, toll-fraud prevention, and topology hidingRaise the team’s voice fluency: the documentation, runbooks, and reviews that make this stack legible to every engineer hereWhat We’re Looking For5+ years building and operating real-time voice systems in production, with hands-on Kamailio and FreeSWITCH depthYou can hold your own on SIP and RTP: location services, dialog state, transfers, Path routing, NAT traversal, and what happens to media when a packet arrives lateYou’ve debugged live production calls from a packet capture and a SIP trace to root causeYou treat config as code and infrastructure as reproducibleFluency using AI as a multiplier across diagnosis, analysis, and testingA clear communicator who writes things downA collaborative, low-ego approach — everyone here sweeps the floorBonus: rtpengine, Homer/HEP for capture and call-leg correlation, SIPp regression suites, Prometheus exporters for the voice plane, or STIR/SHAKEN and carrier interconnectExtra bonus: WebRTC internals (ICE, DTLS-SRTP, TURN) and bridging WebRTC to SIPWhy Join Tin CanWe’re building tech that protects childhood: We’re on a quest to give kids a more analog childhood — one with real conversations, real connection, and way less screen time. No doomscrolling, data mining, or dopamine traps — just a simpler, better way for kids to stay in touch. This is a rare opportunity to build something that truly <matters.You>’ll own the call path outright: This is the first role dedicated entirely to our voice stack — the systems that decide whether a kid’s call connects and how it sounds. You’ll set the direction for how calling works as we scale.Small, high-trust team: Every company says “team,” but at Tin Can it means something different. We’re a small, mission-driven group that genuinely has each other’s backs — professionally and personally. You’ll be joining a tight-knit crew where your ideas and instincts matter from day <one.Room> to explore, not just execute: You’ll have the space to challenge assumptions, solve hard problems, and build systems that reflect our values of trust, simplicity, and care.If you’re excited by the idea of owning the systems that carry a kid’s voice to the people who matter most, and making them so dependable that nobody has to think about them, we’d love to meet you.