Provide Escalated (Tier 3) support for FoIP and SIP-related technical issues via email, phone and case management system (Zendesk).
Diagnose and troubleshoot SIP signaling, call setup failures, one-way audio, jitter, latency, and packet loss.
Analyze SIP traces, PCAP captures, and logs using tools like Wireshark and tcpdump.
Support T.38 Fax Over IP (FoIP) implementations, troubleshooting failed fax transmissions and improving reliability.
Work with PBX systems (Asterisk, FreePBX, 3CX, etc.), VoIP gateways, and SBCs.
Assist customers with network configurations, NAT traversal and firewall rules.
Escalate complex issues to engineering teams and collaborate with vendors as needed.
Take ownership of reported customer issues and see problems through to resolution, ensuring proper recording and closure of all issues.
Write documentation, knowledge base articles and FAQs, and document troubleshooting steps, best practices and solutions in the company's knowledge base for use by both internal staff and customers.
Test interoperability of new VoIP/FoIP equipment and create user guides for various IP-PBX and SIP-compatible devices for use with our SIP Trunking service.

Bachelor's Degree in Computer Science or related field, or combination of education and experience may be considered.
Solid understanding of networking fundamentals (TCP/IP, DNS, DHCP, NAT, VPNs and firewall rules) and networking protocols, in particular VoIP/SIP.
Experience with fax and/or FoIP a plus.
Experience with Wireshark.
Experience with Asterisk, Kamailio, FreeSWITCH, OpenSIPS, or cloud-based VoIP APIs (Twilio, Plivo, Telnyx, etc.).
Working knowledge of Linux/Unix Operating System.
Careful, methodical approach to troubleshooting complex technical issues.
Experience with help desk ticketing systems (Zendesk, Jira, ServiceNow, etc.).
Excellent written and verbal communications including the ability to explain complex technical concepts to customers.
Excellent customer-facing skills.

Senior Technical Support Engineer – SIP, VoIP, FoIP

Key skills