Senior VoIP Engineer

About the role

We are seeking a highly experienced Senior VoIP Engineer to own the design, deployment, and operation of our carrier‑grade voice platform. You will run a multi‑region SIP infrastructure spanning Lagos and the United States, manage interconnects with carriers and wholesale partners, and build the software and automation that keeps it reliable at scale.

Key responsibilities

• Architect, deploy, and operate FreeSWITCH and Kamailio based voice infrastructure across multiple regions and data centers.
• Design and maintain SIP trunking and interconnects with carriers, wholesale providers, and DID suppliers, including routing, least‑cost routing, and failover.
• Engineer the network layer for real‑time media: NAT traversal, RTP/SRTP, TLS, QoS, and cross‑border latency optimization.
• Build and maintain cloud infrastructure on AWS (EKS, VPC, networking, IAM) using infrastructure‑as‑code, focusing on high availability and disaster recovery.
• Develop tooling and services around the voice platform – call routing logic, CDR pipelines, billing integration, provisioning APIs, and monitoring.
• Implement call‑quality monitoring and observability (MOS, jitter, packet loss, ASR/ACD, PDD) and lead root‑cause analysis of voice incidents.
• Secure the platform against toll fraud, SIP scanning, and abuse; manage SBC policies, rate limits, and access controls.
• Support mobile and backend teams on SIP client integration, WebRTC gateways, and push‑based call delivery.
• Own on‑call for voice infrastructure, drive incident response, post‑mortems, and reliability improvements.

Required profile

• Bachelor's or Master's degree in Computer Science, Telecommunications, Electrical Engineering, or related field.
• 7+ years of professional experience building and operating VoIP systems in production.
• Expert‑level knowledge of SIP, SDP, RTP/RTCP, SRTP, DTMF, and codec negotiation (Opus, G.711, G.729).
• Hands‑on production experience with FreeSWITCH and Kamailio or OpenSIPS, including dial‑plan design, ESL/Lua scripting, and dispatcher/routing modules.
• Strong networking foundation: TCP/IP, UDP, NAT, firewalls, BGP/peering concepts, VLANs, QoS, and packet analysis with Wireshark, sngrep, or tcpdump.
• Solid cloud engineering experience on AWS – EKS/Kubernetes, VPC networking, load balancers, Terraform or equivalent, CI/CD.
• Software engineering proficiency in at least one of Kotlin, Java, Go, Python, or C/C++.

Required skills

• FreeSWITCH
• Kamailio (or OpenSIPS)
• SIP, SDP, RTP/RTCP, SRTP, DTMF
• Opus, G.711, G.729 codecs
• TCP/IP, UDP, NAT, BGP, VLANs, QoS
• Wireshark, sngrep, tcpdump
• AWS, EKS, Kubernetes, VPC, Terraform, CI/CD
• Kotlin, Java, Go, Python, C/C++
• Prometheus, Grafana, Homer/SIPCapture, ELK
• Kafka

What we offer

• Competitive salary and performance bonuses.
• Professional growth opportunities, including training and certifications.
• Flexible work arrangements and a collaborative team culture.