2 months ago
Base Salary
$175k - $195k/yr
Responsibilities
- Own Tin Can’s production SIP and media plane, including Kamailio, FreeSWITCH, and carrier trunking.
- Review call-path changes and author SIP test scenarios that gate voice changes before release.
- Write and maintain Kamailio routing logic, including dispatcher, registrar, usrloc, htable, DMQ replication, and TLS configuration.
- Build FreeSWITCH dial plans and integrations using ESL, mod_xml_curl, Lua, and Sofia profiles.
- Measure and operationalize call quality metrics including MOS, jitter, packet loss, and setup time.
- Model and load-test concurrent calls, calls per second, and trunk capacity against peak demand.
- Extend the SIP and media layer into new countries with market-specific codec and emergency-calling requirements.
- Harden signaling and media using SIP over TLS, SRTP, rate limiting, toll-fraud prevention, and topology hiding.
- Improve team fluency through documentation, runbooks, and technical reviews.
Requirements
- 5+ years of experience building and operating real-time voice systems in production.
- Hands-on depth with Kamailio and FreeSWITCH.
- Strong knowledge of SIP and RTP, including location services, dialog state, transfers, Path routing, NAT traversal, and late-packet media behavior.
- Ability to debug live production calls from packet captures and SIP traces through root cause and resolution.
- Experience treating configuration as code and infrastructure as reproducible.
- Fluency using AI for diagnosis, analysis, and testing.
- Clear written and verbal communication skills and a collaborative, low-ego working style.
- Preferred experience with rtpengine, Homer/HEP, SIPp regression suites, Prometheus exporters, STIR/SHAKEN, or carrier interconnect.
- Additional preferred experience with WebRTC internals, including ICE, DTLS-SRTP, and TURN, and with bridging WebRTC to SIP.
Benefits
- Opportunity to build technology intended to give children a safer, more analog way to connect.
- End-to-end ownership of Tin Can’s voice call path and its technical direction.
- Small, high-trust, mission-driven team with room to explore and challenge assumptions.
About Tin Can
Tin Can builds screen-free calling devices and companion services that let kids connect with the people who matter without smartphones. It sells consumer hardware paired with parental controls and onboarding flows designed to get families started quickly and keep kids calling week after week. Privately held and focused on family communications, the company targets households that want kid-friendly connectivity free from the noise of mainstream social media.