Senior Software Engineer, Real-Time Communications

About Tin Can Tin 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 Role A 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 Software Engineer, Real-Time Communications to own the path a kid’s voice takes: how a call routes, how it sounds, and how we know it worked. That path spans two generations — the SIP plane carrying every call today, and the WebRTC handset leg we’re building next. Today that’s Kamailio and FreeSWITCH on AWS, rtpengine at the edge, carrier trunks, and a TypeScript control plane that gates every call. Next is WebRTC on the handset, bridged into that SIP core, because 911 and the phone network will always speak SIP. It’s a deeply hands-on role: routing logic, media paths, and packet captures every day, not a management chain. You’ll report to the Head of Engineering and own the call itself. When a registration flaps at 3am, you go from trace to root cause to fix. What You’ll Do Own the production voice path end to end — SIP signaling, media, and the carrier trunks behind every outside call Design how WebRTC handsets join that path: signaling, TURN, and the WebRTC-to-SIP bridge that keeps 911 and the phone network reachable Write the routing logic and dialplans behind every call — Kamailio, FreeSWITCH, and our TypeScript control plane — so adding a market is configuration, not code Be the reviewer of record for call-path changes, and author the Sipfront and SIPp scenarios that gate them before they ship Produce the packet-level truth about call quality — MOS, jitter, loss, setup time — and make it trustworthy enough to alarm on Model and load-test call capacity — concurrent calls, calls per second, trunk headroom — against our holiday peak Extend calling into new countries, where codecs, carriers, and emergency-calling rules change market to market Harden the path: SIP over TLS, SRTP, rate limiting, toll-fraud prevention Make this stack legible to every engineer here: the documentation, runbooks, and reviews What We’re Looking For 5+ years building and operating real-time voice or video systems in production, including a stretch where the call path was yours: it broke, you fixed it, and you changed what you measured Deep in SIP and RTP on a production stack — Kamailio, OpenSIPS, FreeSWITCH, Asterisk, Janus, mediasoup, LiveKit, or a CPaaS platform You can hold your own on registration, dialog state, NAT traversal, codecs and jitter buffers, and you’ve taken a live production call from a packet capture to root cause At home in production code as well as config; both reviewed, tested, reproducible Fluency using AI as a multiplier across diagnosis, analysis, and testing; this is how we work, not a nice-to-have A clear communicator who writes things down, and a collaborative, low-ego approach — everyone here sweeps the floor Based in Seattle and ready to work from our office Monday through Thursday; this isn’t a remote role Bonus: Kamailio, FreeSWITCH, or rtpengine; WebRTC internals and bridging WebRTC to SIP; Homer/HEP; E911 or carrier interconnect; STIR/SHAKEN Why Join Tin Can We’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 path a kid’s voice takes: The first role dedicated entirely to how calling works at Tin Can — the SIP plane carrying every call today and the WebRTC generation we’re building next. You’ll set the direction for both. 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 explore new ideas, challenge assumptions, 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.