Senior Voice Engineer

We are seeking a highly technical, hands-on Senior Voice Engineer to join our Unified Communications and Collaboration (UC&C) Solution Engineering team.

This role is focused on deep technical execution rather than people management. The engineer will design, secure, and troubleshoot complex voice environments, owning the hardest Tier 3/Tier 4 escalations involving SIP dialog analysis and advanced call flows, and partnering with the dedicated LAN/WAN, Virtualization, and Cybersecurity teams when issues cross into their domains.

The position is also accountable for verifying that voice and UC systems meet DISA Security Technical Implementation Guide (STIG) requirements.

Key Responsibilities

SIP Signaling and Advanced Call-Flow Troubleshooting

• Serve as the senior escalation point for complex voice incidents, analyzing complete SIP dialogs to isolate signaling failures across multi-hop call paths.
• Troubleshoot and resolve issues in complex scenarios, including attended and blind transfers, call forking, hunt and pilot groups, conferencing, call park, shared lines, simultaneous ring, emergency calling, and cloud/hybrid routing through multiple Session Border Controllers (SBCs).
• Diagnose offer/answer and codec negotiation failures, early media, DTMF mismatches, SRTP key exchange problems, one-way and no-way audio, and media anchoring or bypass issues.
• Interpret and manipulate SIP headers and develop SBC message manipulation and normalization rules to resolve interoperability problems between carriers, call-control platforms, and cloud services.
• Use Wireshark/TShark, SBC debug and trace tools, call-control platform traces, call-detail records, and ladder diagrams to reconstruct call flows and document root cause.
• Deliver written root-cause analyses with permanent corrective actions, and feed lessons learned into design standards and operating procedures shared across supported contracts.

STIG Compliance and Voice Security

• Perform and document compliance assessments of voice, UC, and SBC systems against applicable DISA STIGs and Security Requirements Guides (SRGs).
• Use DISA STIG Viewer, Security Content Automation Protocol (SCAP) Compliance Checker, Evaluate-STIG, and authenticated vulnerability scans to produce and maintain STIG checklists and validate findings.
• Develop and implement remediation for open findings, harden configurations, and build secure configuration baselines that remain compliant through upgrades and changes.
• Provide voice-specific technical input to the Cybersecurity team for Risk Management Framework (RMF) packages, POA&Ms, and Authority to Operate (ATO) activities.
• Implement and troubleshoot SIP over TLS, mutual TLS, SRTP, certificate and PKI management, and secure trunking to carriers and cloud platforms.

Layer 2 and Layer 3 Networking for Voice (in partnership with LAN/WAN teams)

• Apply working knowledge of voice VLANs, 802.1Q trunking, Spanning Tree, LLDP-MED/CDP, Power over Ethernet, and 802.1X/MAB to troubleshoot endpoint registration and call-quality issues.
• Understand routing behavior to identify when routing or asymmetric paths are breaking signaling or media.
• Resolve SIP and RTP traversal issues at SBC demarcation points, and specify firewall, NAT, and port requirements for voice to the network and security teams.
• Define voice and video QoS requirements and validate end-to-end QoS behavior with the LAN/WAN teams.
• Isolate packet loss, jitter, latency, and MTU issues affecting voice using packet captures, interface statistics, and call-quality metrics.

Voice Platform Engineering and Delivery

• Author and review high- and low-level designs, implementation procedures, test plans, and rollback plans for voice and UC solutions.
• Architect and integrate IP telephony, SIP trunking, and SBC platforms.
• Architect enterprise dial plans, E.164 normalization, digit manipulation, route patterns, and carrier and PSTN interconnections.
• Design integrations with Microsoft Teams Phone, Webex Calling, and comparable cloud platforms.
• Mentor and guide the technical work of other engineers through design reviews, peer review of configurations, and knowledge transfer.
• Lead technical engagements with manufacturers, carriers, and SIP service providers on complex defects and interoperability issues.

Cross-Program Technical Authority

• Serve as the voice engineering subject matter expert for multiple DoD contracts, prioritizing technical work across programs.
• Develop common voice architectures, STIG-compliant baselines, and SIP normalization standards that can be applied consistently across contracts and customers.
• Contribute to technical roadmaps, modernization strategies, and capture or proposal efforts.
• Brief program managers, government customers, and executive leadership on technical risks, recommendations, and solution tradeoffs that affect program goals.

Required Experience and Education

• Bachelor's degree and 12 or more years of relevant experience, or a Master's degree and 10 or more years, in VoIP, enterprise telephony, unified communications, network engineering, or a closely related discipline.
• Active Secret clearance required.
• Ability to obtain an IAT Level II certification within the period required by the contract.
• Expert-level, hands-on experience analyzing SIP dialogs and SDP negotiation in packet captures and platform traces to resolve complex, multi-hop call-flow failures.
• Demonstrated experience performing DISA STIG compliance checks, completing STIG checklists, and remediating findings on voice, UC, or network infrastructure.
• Solid working knowledge of enterprise switching and routing, sufficient to troubleshoot voice issues at the network layer and work effectively with dedicated network teams.
• Hands-on experience with at least one enterprise call-control platform and at least one enterprise SBC.
• Ability to explain complex technical issues, risks, and recommendations clearly to engineers, customers, and program and executive leadership.

Preferred Technical Proficiencies

• Advanced knowledge of SIP, SDP, RTP/RTCP, SRTP, TLS, H.323, MGCP, and ISDN/PRI.
• Experience with DISA STIG Viewer, SCAP Compliance Checker, Evaluate-STIG, ACAS/Tenable Nessus, and RMF artifacts.
• Familiarity with SD-WAN, MPLS, and carrier transport as they affect voice and video quality.
• Familiarity with VTC and collaboration endpoints.
• Scripting experience with Python, PowerShell, or REST/AXL APIs.
• Experience supporting large-scale, geographically distributed, highly available DoD or mission-critical voice networks.

Preferred Certifications and Qualifications

• Cisco Certified Network Professional (CCNP) Collaboration or Cisco Certified Internetwork Expert (CCIE) Collaboration.
• Cisco CCNA or equivalent networking certification.
• CompTIA Security+ CE or other DoD 8140 IAT Level II certification.