Introduction 2–4 years' hands-on Linux and VoIP experience

TYPE:  Permanent

LEVEL: Junior - Tier 2 - 3  |  Level 2 - 3 - Mid-level

LOCATION:  Claremont - Western Cape - Cape Town - onsite

This is an L2–L3 VoIP Engineer role built for someone who's ready to stop assisting and start owning.

Essential – Linux

2–4 years' hands-on Linux administration in production (Debian/Ubuntu and/or RHEL-family: Rocky, AlmaLinux, CentOS). Command-line fluency: systemctl, journalctl, grep/awk/sed, ps, top/htop, ss, lsof, df/du. Linux networking: ip and routing, tcpdump, dig, iptables / nftables / firewalld. Bash scripting; cron or systemd timers; package management (apt / dnf / yum), patching, users and permissions, SSH. Working knowledge of a database (MariaDB / MySQL / PostgreSQL) and a web server.

Essential – VoIP and networking

SIP call flow (INVITE → 100/180 → 200 OK → ACK → BYE) and core response codes: 401, 403, 404, 486, 503. RTP/RTCP, codecs (G.711 / G.729) and DTMF methods (RFC 2833, SIP INFO, in-band). Hands-on with at least one telephony platform: Asterisk, FreePBX/Issabel, FreeSWITCH, Kamailio/OpenSIPS, VICIdial, 3CX or Wazo. Wazo is Asterisk-based, so Asterisk experience transfers. Networking: IP addressing, TCP/UDP, NAT (and why it breaks VoIP), DNS including SRV records, firewall basics. Strong troubleshooting instincts, shown through real examples — not just theory.

Advantageous

RHCSA / RHCE, LPIC-1 / LPIC-2, CompTIA Linux+ or LFCS; CCNA or Network+. SBCs and proxies: Kamailio, OpenSIPS, AudioCodes, RTPEngine. Ansible, Docker, Python; monitoring with Zabbix, Nagios, Prometheus or Grafana; Homer/HEP capture. Diploma or degree in IT, Computer Science, Networking or Telecoms.

Duties & Responsibilities  

What you will do

Linux platform engineering Build, patch, harden and monitor the Linux servers (Debian/Ubuntu and RHEL-family) that run the voice platform. Manage services with systemd; investigate failures using journalctl and application logs. Configure host firewalls (iptables / nftables / firewalld) and fail2ban; manage SSH access and key-based authentication. Administer supporting services: MariaDB / MySQL / PostgreSQL, web servers and log handling. Automate routine work with bash and Python (Ansible is a plus); look after disk, backups and capacity. Voice platform Administer and maintain Asterisk PBX and Wazo E-UC — extensions, dialplans and trunks. Configure and maintain SIP trunks and carrier interconnects: authentication, codecs, DTMF mode and NAT settings. Troubleshooting and incident response (Tier 2) Own Tier-2 escalations: one-way audio, registration failures, call-quality issues (jitter, packet loss), DTMF faults, codec mismatches and routing problems. Find root cause with Wireshark, sngrep, Homer and tcpdump — reading SIP INVITE/200/ACK/BYE flows, SDP and RTP streams. Watch platform health dashboards, investigate anomalies and take corrective action. Change and maintenance Run or co-lead scheduled off-peak maintenance windows; write and follow MOPs (Method of Procedure) including rollback; validate with post-change test calls. Working practice Keep Jira tickets, documentation and runbooks current; support a more junior engineer where there is one.

Desired Experience & Qualification Must Have

2–4 years' hands-on experience with Linux and VoIP/SIP in a production environment. Comfortable in Linux at a working level: CLI navigation, reading logs, checking and restarting service status without guidance. Direct, hands-on administration experience with Asterisk PBX, FreePBX, 3CX, or Wazo E-UC — has configured extensions, dialplans, and trunks, not just observed them. Has configured or maintained SIP trunks and carrier interconnects independently. Solid networking fundamentals: IP addressing, TCP/UDP, NAT, DNS, firewall basics — including why NAT specifically matters for VoIP. Fluent in core SIP response codes (401, 403, 404, 486, 503) and what each indicates. Comfortable reading SIP and RTP traffic in Wireshark or Homer without step-by-step supervision. Exposure to SBCs (Kamailio, OpenSIPS, AudioCodes, or similar) beyond Asterisk/Wazo alone. Scripting/automation exposure (bash, Python) for monitoring or routine platform tasks. Experience with Jira or a similar ticketing/task-management tool. Some experience mentoring or supporting a more junior engineer. Able to independently triage and resolve Tier-2 issues — call-quality degradation, one-way audio, registration failures — escalating only genuinely complex or platform-wide faults. Confident running or co-leading maintenance windows, including writing or following a MOP with minimal oversight. Strong troubleshooting instincts, evidenced by real examples — not just theory. Available to attend periodic maintenance windows during off-peak hours.

Qualifications

Matric / Grade 12. Diploma or degree in IT, Networking, Telecoms or Computer Science (advantageous). CompTIA Network+, Linux+, CCNA, or a VoIP/UC-specific certification (advantageous).

Package & Remuneration Market Related - Including Benefits

Interested? Who we will consider

Engineers who are strong on Linux and comfortable with voice are rare, so we are open to several backgrounds:

VoIP / telecoms engineers with strong Linux. Linux sysadmins and support engineers (hosting, data centre, MSP) who understand SIP, RTP and codecs and want to specialise in voice. DevOps, SRE and infrastructure engineers with solid Linux and monitoring experience. ISP, NOC and network engineers with Linux and SIP/carrier exposure. Call-centre dialler and telephony administrators (VICIdial, Issabel, Elastix, GoAutoDial). Developers who have scripted or integrated Asterisk, FreeSWITCH or Kamailio.

Not the right fit: desktop support, help desk or call-centre agent roles without hands-on Linux administration, regardless of years of tenure.

VoIP Engineer | Linux Engineer

Required Skills

Job Description