{"id":2527494,"url":"https://alion.io/job/practice-numbers-senior-software-engineer-core-voip-sip-backbone","title":"Senior Software Engineer – Core VoIP / SIP Backbone","company":{"id":2763798,"name":"Practice Numbers","domain":"practicenumbers.com","url":"https://alion.io/company/practicenumbers","size_band":null,"is_staffing_agency":false,"employer_type":"direct","is_intermediary":false,"listed_via":null,"ats_vendor":"Gem","truth_index":null},"role":"Networking","role_family":"Networking","seniority":"senior","employment_type":"full_time","work_mode":"hybrid","remote_scope":null,"remote_scope_basis":null,"remote_working_hours":null,"hiring_geo_confidence":"structured","locations":["Bellevue, United States"],"countries":["US"],"hiring_countries":[],"hiring_countries_total":0,"salary":{"min":150000,"max":180000,"currency":"USD","period":"year","gross":null,"usd_annual":180000},"salary_estimate":null,"experience_years_min":7,"visa_sponsorship":false,"relocation_package":false,"has_equity":false,"technologies":[{"name":"AI Agents","optional":false},{"name":"Go","optional":false},{"name":"Linux","optional":false},{"name":"MariaDB","optional":false},{"name":"MySQL","optional":false},{"name":"PostgreSQL","optional":false},{"name":"Tcpdump","optional":false},{"name":"Wireshark","optional":false},{"name":"AWS","optional":true},{"name":"GCP","optional":true},{"name":"Kubernetes","optional":true},{"name":"WebRTC","optional":true},{"name":"WebSockets","optional":true}],"status":"closed","first_seen_at":"2026-07-02T21:22:41Z","employer_posted_date":"2026-07-02","last_verified_at":"2026-10-15T02:53:09Z","board_verified":false,"closed_at":"2026-10-15T02:53:09Z","days_open":104,"trust":{"level":"not_scored","repost_count":null,"flags":[],"days_open":104},"description":"Senior Software Engineer - Core VoIP / SIP Backbone\nLocation: Hybrid , Bellevue WA\nEmployment Type: Full-Time\nCompensation: $150K- 180K base salary, depending on experience + equity + benefits\nAbout Practice by Numbers\nPractice by Numbers (PBN) is a leading dental practice management SaaS platform serving over 5,000 dental practices across North America. Our platform delivers practice management, VoIP telephony, payments, and advanced analytics. We are evolving into an AI-first product, adding conversational automation and intelligent communication workflows for patients and front-office teams.\nAbout the Role\nThis role owns the design and implementation of the core VoIP/SIP telephony backbone for PBN, including SIP routing, media handling, scalability, and reliability. You will architect and build Golang-based SIP services and control planes on top of open-source components such as Kamailio (or similar SIP server), FreeSWITCH/OpenSIPS, and related media/RTP proxies. This is a senior individual contributor role with high ownership and direct impact on a product used by thousands of dental practices daily.\nKey Responsibilities\nDesign and implement a carrier-grade SIP/VoIP core using components like Kamailio/OpenSIPS for SIP signaling and FreeSWITCH or similar for media and application services.\nBuild Golang-based SIP services (registrar, SBC-like components, routing logic, monitoring daemons) and internal APIs to control routing, policies, and provisioning.\nConfigure and operate SIP load balancing, failover, and high-availability setups (multi-node SIP proxies, distributed media servers, RTP proxies).\nImplement and maintain dial plans, least-cost routing, DID management, class-4/class-5 style switching logic, and integration with upstream carriers and PSTN gateways.\nOwn security and robustness of the VoIP stack: TLS/SRTP, authentication/authorization, rate limiting, fraud detection hooks, and abuse controls.\nIntegrate the telephony backbone with PBN's SaaS platform (user accounts, billing, analytics, AI/automation flows) via well-defined internal APIs and webhooks.\nDefine monitoring, alerting, logging, and capacity planning for SIP signaling, RTP/media, and VoIP quality (MOS, jitter, packet loss).\nCollaborate with product and operations teams to translate business requirements (IVRs, call queues, routing rules, AI agents) into resilient VoIP and backend designs.\nRequired Qualifications\n7-10 years of software development experience with at least 4-5 years building or operating large-scale VoIP/SIP systems.\nStrong Golang skills, including building high-performance networked services, concurrent processing, and production-grade APIs.\nHands-on experience with at least one open-source SIP server such as Kamailio/OpenSIPS and one media/application server such as FreeSWITCH or Asterisk, including configuration, routing logic, and troubleshooting.\nDeep understanding of SIP, RTP, SDP, NAT traversal, registrar/registrations, B2BUA vs. proxy behavior, and SBC concepts.\nProven ability to design and run highly available telephony backbones: clustering, health checks, load balancing, and graceful failover.\nStrong Linux and networking fundamentals (iptables, firewalls, TCP/UDP, QoS), comfortable debugging at packet level using tcpdump/Wireshark.\nExperience integrating VoIP platforms with RESTful backends, databases (PostgreSQL or MariaDB/MySQL), and message queues for control and billing workflows.\nNice to Have\nExperience with WebRTC, SIP over WebSockets, and browser/mobile softphone integrations.\nFamiliarity with VoIP billing, rating engines, CDR processing, and reseller hierarchies (class-4/class-5 softswitch products or similar).\nCloud-native deployment of VoIP stacks (containerized Kamailio/FreeSWITCH clusters on AWS/GCP, Kubernetes, service meshes).\nPrior work building call center or CPaaS-style platforms, including programmable IVRs, queues, and analytics.\nWhat Success Looks Like\nA robust, observable VoIP backbone that sustains high call volumes with low failure rates and predictable call quality across geographies.\nRapid rollout of new telephony features (IVRs, routing rules, AI agents) through clean APIs and configuration-driven behavior rather than manual changes.\nDemonstrated reduction in telephony incidents and MTTR through automation, strong monitoring, and clear runbooks.\nBenefits & Perks\nCompetitive base salary (Salary range) + equity\nComprehensive medical, dental, and vision insurance\n401(k) with company match\nFlexible PTO and paid holidays\nCompensation\nThe base pay range for this role is $150 - $180 per year.","description_format":"text","description_chars":4593,"description_truncated":false,"requirements":{"experience_years_min":7,"management_years_min":null,"team_size_min":null,"manages_managers":false,"education":null,"security_clearance":false,"languages":[]},"benefits":["Equity","Vision insurance"],"hiring_locations":[{"name":"United States","iso":"US","kind":"country"}],"hiring_excludes":[],"relocation_offered":false,"industries":[],"lifecycle":[{"event":"open","at":"2026-10-14T12:25:24Z"},{"event":"close","at":"2026-10-15T02:53:09Z"}],"visa":[],"liveness":null,"pay":{"stated_usd_annual":180000,"is_top_pay":true},"html_url":"https://alion.io/job/practice-numbers-senior-software-engineer-core-voip-sip-backbone","json_url":"https://alion.io/job/practice-numbers-senior-software-engineer-core-voip-sip-backbone.json","meta":{"generated_at":"2026-10-15T10:40:26Z","cache_seconds":300,"methodology":"https://alion.io/methodology","terms":"https://alion.io/terms","contact":"https://alion.io/contact","api":"https://alion.io/developers","about":"Alion is a live layer of people, companies and AI agents: who they are, whether they are real and active right now, what they do and how to work with them, readable by people and by agents and paid per call.","catalog":"https://alion.io/catalog.json","usage":{"tier":"crawler_verified","counted_by":"address","units_charged":1,"used_today":16160,"day_limit":null,"remaining_today":null,"minute_limit":300,"resets_at":"2026-10-16T00:00:00Z"}},"offers":[{"id":"company.slices","title":"One company in depth, by slice","status":"live","price":{"credits":0.02,"usd":0.002,"plus_per_slice":{"credits":0.05,"usd":0.005}},"unit":"per company, plus each slice with data","note":"the employer in depth","call":{"mcp_tool":"get_company","arguments":{"id":2763798},"rest":"https://alion.io/mcp/rest/get_company?id=2763798"},"human":"https://alion.io/catalog?offer=company.slices&for=job%2Fpractice-numbers-senior-software-engineer-core-voip-sip-backbone"},{"id":"market.stats","title":"A market slice: pay, demand and time to fill","status":"live","price":{"credits":1,"usd":0.1},"unit":"per slice","note":"pay, demand and time to fill for this role and place","call":{"mcp_tool":"market_stats"},"human":"https://alion.io/catalog?offer=market.stats&for=job%2Fpractice-numbers-senior-software-engineer-core-voip-sip-backbone"},{"id":"job.search","title":"Open jobs by role, technology, place, pay and visa","status":"live","price":{"credits":0.02,"usd":0.002},"unit":"per posting in a list","note":"similar open postings","call":{"mcp_tool":"search_jobs"},"human":"https://alion.io/catalog?offer=job.search&for=job%2Fpractice-numbers-senior-software-engineer-core-voip-sip-backbone"},{"id":"company.verify","title":"Is this company real and active right now","status":"pilot","price":null,"unit":"per company","request":{"url":"https://alion.io/catalog/request","method":"POST","body":"{\"offer\": \"company.verify\", \"for\": \"job/practice-numbers-senior-software-engineer-core-voip-sip-backbone\", \"note\": \"what you need it for\"}"},"human":"https://alion.io/catalog?offer=company.verify&for=job%2Fpractice-numbers-senior-software-engineer-core-voip-sip-backbone"}]}