Requirements: Senior-level experience with Linux administration in distributed production environments; Strong production expertise with Asterisk, FreePBX, SIP, RTP, SDP, and IP telephony; Ability to analyze SIP messages, packet captures, dialplans, and end-to-end call flows; Solid knowledge of TCP/IP, UDP, DNS, DHCP, NAT, firewalls, VLANs, TLS, and Linux networking; Experience managing SIP phones, provisioning, firmware, carrier trunks, and number routing; Strong scripting skills in Bash, Python, or a similar language; Experience with Git, configuration management, monitoring, and incident response. Responsibilities: Maintain, secure, and update a distributed Linux infrastructure and its voice services; Manage SIP phone provisioning, configurations, firmware, and certificates; Support SIP trunks, call routing, failover, caller ID, and carrier integrations; Automate fleet management, deployments, and recovery processes; Monitor production systems, investigate incidents, and eliminate recurring issues; Troubleshoot Asterisk, FreePBX, SIP, RTP, DTMF, NAT, routing, and audio problems.