VoIP Engineer | Asterisk / FreeSWITCH

We are looking for a VoIP Engineer to support and develop production telephony based on Asterisk and FreeSWITCH.

We need a specialist with practical experience in VoIP who can independently diagnose complex issues with SIP/RTP, configure routing, and work with production infrastructure.

Main Tasks:

• Support the stability and availability of Asterisk / FreeSWITCH • Configure and maintain SIP trunks, gateways, endpoints, registrations • Configure inbound and outbound call routing • Work with dialplan, IVR, queues, call forwarding • Diagnose issues with call setup and call quality • Analyze SIP traffic, RTP, CDR, logs, and network captures • Monitor the platform and respond to incidents • Participate in production troubleshooting and RCA • Interact with telecom providers and technical teams • Document configurations and changes • Participate in on-call rotation if necessary

Must-Haves:

• Practical experience with Asterisk / FreeSWITCH • Deep understanding of SIP, SDP, RTP • Ability to read and analyze SIP traffic • Understanding of SIP codes 4xx / 5xx / 6xx • Experience with dialplan and call routing • Understanding of SIP trunks, gateways, endpoints, and registrations • Ability to diagnose: — no / one-way audio — jitter and packet loss — latency — dropped calls — call setup issues • Confident Linux troubleshooting • Understanding of NAT, Firewall, SIP/RTP ports • Practical experience with tcpdump, sngrep, ss, dig, ping, traceroute • Work with Asterisk / FreeSWITCH logs and system logs • Git • Experience with safely making changes in production and understanding rollback procedures

Bonus Points:

• Kamailio / OpenSIPS / SBC / RTPengine • PJSIP / FreeSWITCH Sofia • AMI / ARI / AGI / ESL • Telephony integrations with CRM / REST API / WebSocket • Python / Bash / Lua • Docker / Kubernetes • Ansible / Terraform • Prometheus / Grafana / Zabbix • WebRTC, TLS / SRTP, QoS • Experience with HA / failover • VoIP Security: toll fraud, SIP scanning, brute-force, Fail2Ban, ACL, rate limiting • Understanding of ASR, ACD, PDD, MOS, CPS

Languages:

Russian — fluent English — for technical documentation and communication with international providers

Conditions:

5/2, 09:00–18:00 Modern VoIP infrastructure Professional development opportunities