Role: Senior VoIP/SIP Engineer

Function: Engineering

Location: Kolkata / Gurugram, India

Type: Full-time

Compensation: Not specified

Industry: SaaS, Healthcare Technology, Telecommunications

About Company

A dental practice management SaaS platform serving 1,500+ practices across North America. Founded by a practicing dentist who experienced operational challenges firsthand.

The platform combines practice management, VoIP telephony, payments, and advanced analytics. The company is evolving into an AI-first product with conversational automation and intelligent communication workflows.

Position Overview

You will own the design and implementation of the core VoIP/SIP telephony backbone that powers communication for thousands of dental practices. You'll architect and build carrier-grade Golang-based SIP services on top of open-source components like Kamailio and FreeSWITCH. This role offers direct impact on a critical platform component serving over 1,500 practices while working closely with the Engineering India Head.

Role & Responsibilities

• Design and implement a carrier-grade SIP/VoIP core using components like Kamailio/OpenSIPS for SIP signaling and FreeSWITCH for media and application services
• Build Golang-based SIP services including registrar, SBC-like components, routing logic, monitoring daemons, and internal APIs to control routing, policies, and provisioning
• Configure and operate SIP load balancing, failover, and high-availability setups with multi-node SIP proxies, distributed media servers, and RTP proxies
• Implement and maintain dial plans, least-cost routing, DID management, class-4/class-5 style switching logic, and integration with upstream carriers and PSTN gateways
• Own security and robustness of the VoIP stack including TLS/SRTP, authentication/authorization, rate limiting, fraud detection hooks, and abuse controls
• Integrate the telephony backbone with the company's SaaS platform via well-defined internal APIs and webhooks for user accounts, billing, analytics, and AI/automation flows
• Define monitoring, alerting, logging, and capacity planning for SIP signaling, RTP/media, and VoIP quality metrics including MOS, jitter, and packet loss
• Collaborate with product and operations teams to translate business requirements for IVRs, call queues, routing rules, and AI agents into resilient VoIP and backend designs

Must Have Criteria

• 7-10 years of software development experience with at least 4-5 years building or operating large-scale VoIP/SIP systems
• Strong Golang skills including building high-performance networked services, concurrent processing, and production-grade APIs
• Hands-on experience with at least one open-source SIP server such as Kamailio/OpenSIPS and one media/application server such as FreeSWITCH or Asterisk
• Deep understanding of SIP, RTP, SDP, NAT traversal, registrar/registrations, B2BUA vs proxy behavior, and SBC concepts
• Proven ability to design and run highly available telephony backbones including clustering, health checks, load balancing, and graceful failover
• Strong Linux and networking fundamentals including iptables, firewalls, TCP/UDP, QoS, and comfort debugging issues at packet-level using tools like tcpdump/wireshark
• Experience integrating VoIP platforms with RESTful backends, databases (PostgreSQL or MariaDB/MySQL), and message queues for control and billing workflows

Nice to Have

• Experience with WebRTC, SIP over WebSockets, and browser/mobile softphone integrations
• Familiarity with VoIP billing, rating engines, CDR processing, and reseller hierarchies (class-4/class-5 softswitch products or similar)
• Cloud-native deployment of VoIP stacks including containerized Kamailio/FreeSWITCH clusters on AWS/GCP, Kubernetes, and service meshes
• Prior work building call center or CPaaS-style platforms including programmable IVRs, queues, and analytics

What We Offer

• In-office work environment in Kolkata or Gurugram
• Opportunity to build telephony infrastructure serving 1,500+ dental practices
• Direct reporting to Engineering India Head
• Work on AI-first product evolution with conversational automation