Senior SIP Engineer

Telegent, Inc.•Pleasant Grove, UT

About The Position

Telegent is building a programmable mobile network that enables call routing, call transfers, filtering, receptionist features, and AI-native workflows on real mobile numbers, including without a SIM or device. The Senior SIP Engineer will own the voice stack and develop reliable, scalable voice infrastructure and products. The role covers call routing across SBCs, media servers, and carrier trunks; carrier and customer interconnects; programmable voice features; AI voice products; migration from legacy voice platforms; caller trust and compliance; and operational reliability. The engineer will work across SIP proxies and SBCs, media proxies, application servers, programmable voice services, carrier trunks, speech and AI services, monitoring, and cloud infrastructure. The team works quickly, uses AI-driven coding workflows, makes small reversible changes, and expects engineers to take systems from design through production and operations. The first deliverable is an assessment and 100-day plan. Systems are built with security and SOC 2 controls in mind, and architecture decisions are documented as ADRs.

Requirements

Deep knowledge of SIP and RTP, including SIP traces, SDP, codecs such as G.711, G.729, AMR-WB, and EVS, NAT traversal, and media handling.
Production experience with OpenSIPS or Kamailio and FreeSWITCH or Asterisk at carrier scale.
Experience with carrier SIP trunking, number routing, IP-based peering, and US requirements including STIR/SHAKEN, CNAM, and E911.
Hands-on experience setting up P-CSCF, I-CSCF, S-CSCF, and HSS, and understanding end-to-end VoLTE and VoWiFi call flows.
Ability to troubleshoot using tools such as Wireshark, sngrep, SIPp, Homer, or VoIPmonitor.
Ability to build services and tooling in Python, Go, or TypeScript; work with Redis and REST APIs; and operate Linux, Terraform, and cloud networking, with Azure as the first cloud.
Practice in enterprise-grade agentic coding and fluency across coding clients and harnesses; bring an established setup of agents, skills, and automations and ideas for improving the team's workflows.
Ownership and judgment to take work from idea to production, raise problems early, and help guide the team.
Deep understanding of SIP registration and REGISTER/auth flows, NAT traversal, SDP/RTP, codecs, SIP trunking, and WebRTC paths for integrations with unified communications and video platforms such as Zoom, Microsoft Teams, and Webex.
Experience setting up and configuring SBCs, including topology hiding, transcoding, security, and interoperability.
Knowledge of call routing, number and LCR routing, failover, and STIR/SHAKEN.
Experience putting AI voice agents on real calls, streaming media to AI while keeping latency low enough for natural conversations.
Knowledge of agentic coding practices, including worktree management and multi-agent workflows; skills, hooks, and routines; token optimization; plan mode; and structured methods such as SDD, TDD, SpecKit, and role-based development.
End-to-end systems lifecycle and full-stack development experience, including deploying systems at scale with observability.

Nice To Haves

Experience with jambonz or building CPaaS voice APIs, including call control, webhooks, and media streams.
Experience running voice services across multiple clouds and colocation sites.
Experience building systems to SOC 2 controls from the first line of code.

Responsibilities

Design and operate call routing across the network, SBCs, media servers, and carrier trunks, including keeping calls between Telegent numbers on its own network.
Bring new SIP trunks and interconnects online and serve as a technical expert for partners troubleshooting call failures.
Build programmable voice features, including call-control APIs, webhooks, recording, IVR, and real-time audio streaming to AI.
Work with product teams on call screening, scam detection, and AI voice agents that operate on live calls.
Migrate traffic from legacy third-party voice platforms to direct SIP trunks without downtime.
Own STIR/SHAKEN, caller ID (CNAM), and recording consent to support trusted and compliant calling.
Build reliability at scale through redundant SBCs, geographic routing, capacity planning, monitoring, and disaster recovery.
Trace failed calls through SIP logs and packet captures, fix root causes, and turn fixes into tests or runbooks.
Record decisions as ADRs, review code, and make voice technology approachable to other engineers.
Assess work, benchmark options, prepare solutions, and deliver an assessment and 100-day plan.
Own systems from implementation through production and operations, without hand-offs to a separate operations team.