Senior SIP/VoIP FoIP Engineer (Remote)

T38Fax LLC; Philadelphia (Philadelphia County); Hybrid; USD 90,000 - 120,000; Full time

Benefits offered by this job

Profit-sharing bonus

Casual work environment

Remote/hybrid options

Generous PTO

Healthcare

401(k)

Flyers season tickets

Team of aces

Open to new ideas

Job summary

T38Fax LLC is seeking an experienced Technical Support Engineer to troubleshoot SIP, VoIP, and FoIP issues in a customer-facing role. You will diagnose calls, analyze traces, and support T.38 FoIP deployments from a senior perspective.

We value strong networking knowledge, Wireshark expertise, and the ability to document solutions. This role offers flexible remote/hybrid work options and competitive compensation in the US market.

Qualifications

• Bachelor's Degree in Computer Science or related field or combination of education and experience.
• Strong understanding of networking fundamentals (TCP/IP, DNS, DHCP, NAT, VPNs and firewall rules) and VoIP/SIP.
• Experience with fax and/or FoIP is a plus.
• Experience with Wireshark.
• Experience with Asterisk, Kamailio, FreeSWITCH, OpenSIPS, or cloud-based VoIP APIs.
• Working knowledge of Linux/Unix operating systems.
• Familiarity with help desk ticketing systems (Zendesk, Jira, ServiceNow).
• Excellent written and verbal communication including the ability to explain complex technical concepts to customers.
• Excellent customer-facing skills.

Responsibilities

• Provide Escalated (Tier 3) support for FoIP and SIP-related issues via email, phone and Zendesk.
• Diagnose and troubleshoot SIP signaling, call setup failures, one-way audio, jitter, latency, and packet loss.
• Analyze SIP traces, PCAPs, and logs using Wireshark and tcpdump.
• Support T.38 Fax Over IP (FoIP) implementations and improve reliability.
• Work with PBX systems, VoIP gateways, and SBCs.
• Assist customers with network configurations, NAT traversal and firewall rules.
• Escalate complex issues to engineering and collaborate with vendors.
• Own reported issues and ensure proper recording and closure.
• Write documentation and knowledge base articles for internal and customer use.
• Test interoperability of new VoIP/FoIP equipment and create user guides.

Skills

Troubleshooting

SIP/VoIP basics

Customer-facing

Networking fundamentals

Documentation

Education

Bachelor's Degree in Computer Science or related field

Tools

Wireshark

Zendesk

Jira

ServiceNow

Asterisk

Kamailio

FreeSWITCH

OpenSIPS

Twilio

Plivo

Telnyx

Job description

T38Fax LLC is seeking an experienced Technical Support Engineer to troubleshoot SIP, VoIP, and FoIP issues in a customer-facing role. You will diagnose calls, analyze traces, and support T.38 FoIP deployments from a senior perspective.

We value strong networking knowledge, Wireshark expertise, and the ability to document solutions. This role offers flexible remote/hybrid work options and competitive compensation in the US market.