Senior VoIP Backbone Engineer — SIP/Golang, Equity

Practice By Numbers, Inc.; Bellevue (WA); Hybrid; USD 150,000 - 180,000; Full time

Benefits offered by this job

Competitive base salary + equity

Medical/dental/vision insurance

401(k) with company match

Flexible PTO and paid holidays

Job summary

Practice by Numbers, Inc. in Bellevue, WA is seeking a Senior Software Engineer to own the core VoIP/SIP backbone.

You will design and implement Golang-based services, integrate with Kamailio/OpenSIPS and FreeSWITCH, and ensure scalable, secure telephony for thousands of dental practices.

This hybrid role offers a competitive salary, equity, and benefits as part of a high-impact SaaS platform.

Qualifications

• 7–10 years of software development with 4–5 years in large-scale VoIP/SIP systems.
• Strong Golang skills with production-grade networked services and APIs.
• Hands‑on experience with Kamailio/OpenSIPS and FreeSWITCH or Asterisk.
• Deep understanding of SIP, RTP, NAT traversal, and SBC concepts.
• Experience designing highly available telephony backbones with clustering and load balancing.

Responsibilities

• Design and implement a carrier-grade SIP/VoIP core using Kamailio/OpenSIPS for signaling and FreeSWITCH for media.
• Build Golang-based SIP services (registrar, routing, monitoring) and internal APIs.
• Configure SIP load balancing, failover, and multi-node high-availability setups.
• Implement dial plans, least-cost routing, DID management, and PSTN gateway integration.
• Own security and robustness of the VoIP stack (TLS/SRTP, rate limiting, fraud controls).
• Integrate telephony backbone with PBN's SaaS platform via internal APIs and webhooks.
• Define monitoring, alerting, logging, and capacity planning for SIP signaling and RTP.
• Collaborate with product/ops to translate requirements into VoIP designs.

Skills

Golang

VoIP/SIP

Linux networking

REST APIs

TCP/UDP networking

SIP signaling

High availability

Tools

Kamailio/OpenSIPS

FreeSWITCH/Asterisk

tcpdump/Wireshark

PostgreSQL/MySQL

Job description

Practice by Numbers, Inc. in Bellevue, WA is seeking a Senior Software Engineer to own the core VoIP/SIP backbone.

You will design and implement Golang-based services, integrate with Kamailio/OpenSIPS and FreeSWITCH, and ensure scalable, secure telephony for thousands of dental practices.

This hybrid role offers a competitive salary, equity, and benefits as part of a high-impact SaaS platform.