Senior Telephony Infrastructure Engineer

PatientNow•New York, NY

About The Position

The Senior Telephony Infrastructure Engineer owns Recura’s real-time communications layer, including voice calling, call routing, and A2P messaging infrastructure. This role is responsible for building and operating deterministic, observable, and compliant telephony systems that behave correctly under carrier retries, partial failures, and real-world edge cases. This is a senior individual contributor role with mentorship expectations. You will design call routing, missed-call detection, and messaging compliance systems that downstream product teams depend on, while insulating them from carrier complexity and failure modes.

Requirements

5+ years of experience building or operating telephony, VoIP, or CPaaS systems.
Hands-on experience with SIP-based calling and WebRTC in production environments.
Experience building call routing systems (schedules, ring groups, IVR, overflow logic).
Experience implementing A2P 10DLC compliance workflows, including brand/campaign lifecycle handling.
Experience with ISV or multi-tenant CPaaS models, including subaccount provisioning.
Strong understanding of event-driven systems, webhook retries, and idempotent processing.
Familiarity with result-based error handling patterns (explicit success/failure states over exceptions).
Prior startup experience (required).

Nice To Haves

Familiarity with modern backend systems (e.g., TypeScript, Postgres) and cloud infrastructure, preferred.

Responsibilities

Design, implement, and operate SIP-based voice infrastructure and WebRTC calling.
Build and maintain call routing systems including schedules, ring groups, IVR, voicemail, and overflow logic.
Design timezone-aware, rules-based routing, including overnight ranges and day-of-week matching.
Implement missed-call, abandoned-call, and after-hours detection with deterministic, idempotent event emission.
Own SMS/MMS carrier integrations, including A2P 10DLC registration workflows and enforcement.
Build and maintain ISV-style subaccount onboarding, including phone number provisioning and messaging service assignment.
Implement answering machine detection (AMD) with async callbacks and configurable detection behavior.
Design VoIP observability systems for call session tracking, event correlation, and production debugging.
Handle phone number lifecycle operations, including migration between messaging services with rollback safety.
Mentor engineers on reliability, event-driven design, and debugging complex production systems.