Description We are seeking a highly technical, hands-on Senior Voice Engineer to join our Unified Communications and Collaboration (UC&C) Solution Engineering team. Reporting to the Voice Team Lead, this individual contributor will serve as a senior subject matter expert for enterprise voice, with practical SIP troubleshooting skills and solid working knowledge of the network infrastructure that carries it.
This role is focused on deep technical execution rather than people management. The engineer will design, secure, and troubleshoot complex voice environments, handling Tier 2 and Tier 3 escalations involving SIP signaling and call-flow issues, 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.
This position supports multiple DoD contracts. As a Level T4 engineer, the incumbent will work independently on complex technical assignments with minimal supervision, apply and help improve the voice engineering standards used across those contracts, and provide technical guidance to less experienced engineers. The position will work closely with Transport Engineering, Network Operations, Cybersecurity, program leadership, customers, and vendor partners.
Key ResponsibilitiesSIP Signaling and Call-Flow Troubleshooting- SIP Dialog Analysis: Troubleshoot voice incidents by reading SIP call flows (INVITE, responses, ACK, BYE, and common mid-call messages) to identify where calls are failing, and escalate complex multi-hop issues to senior engineers.
- Advanced Call Flows: 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).
- Media and SDP Negotiation: Diagnose common media issues such as codec mismatches, DTMF problems, and one-way or no-way audio, using SDP offer/answer and RTP information from packet captures.
- Header and Normalization Analysis: Interpret common SIP headers (such as Via, Contact, P-Asserted-Identity, and Diversion) and implement or modify SBC message manipulation and normalization rules, with guidance from senior engineers, to resolve interoperability problems between carriers, call-control platforms, and cloud services.
- Diagnostic Tooling: 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.
- Root-Cause Analysis: Deliver written root-cause analyses with permanent corrective actions, and contribute lessons learned to design standards and operating procedures.
STIG Compliance and Voice Security- STIG Compliance Checking: Perform and document compliance assessments of voice, UC, and SBC systems against applicable DISA STIGs and Security Requirements Guides (SRGs), including the Voice/Video Services Policy STIG and vendor-specific STIGs.
- Scanning and Validation: Use DISA STIG Viewer, Security Content Automation Protocol (SCAP) Compliance Checker, Evaluate-STIG, and authenticated vulnerability scans to produce and maintain STIG checklists (.ckl/.cklb) and validate findings.
- Remediation: Develop and implement remediation for open findings, harden configurations, and build secure configuration baselines that remain compliant through upgrades and changes.
- Authorization Support: Provide voice-specific technical input to the Cybersecurity team for Risk Management Framework (RMF) packages, POA&Ms, and Authority to Operate (ATO) activities, including justification for deviations and mitigations.
- Secure Signaling and Media: 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)- Layer 2 Switching: 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, and define voice requirements for the LAN team.
- Layer 3 Routing: Understand routing behavior (static, OSPF, EIGRP, BGP, HSRP/VRRP, ACLs) well enough to identify when routing or asymmetric paths are breaking signaling or media, and provide clear evidence to the WAN team for resolution.
- NAT, Firewall, and Traversal: 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.
- QoS: Define voice and video QoS requirements (DSCP and CoS marking, trust boundaries, call admission control) and validate end-to-end QoS behavior with the LAN/WAN teams.
- Network Performance Analysis: Isolate packet loss, jitter, latency, and MTU issues affecting voice using packet captures, interface statistics, and call-quality metrics.
Voice Platform Engineering and Delivery- Design and Documentation: Author high- and low-level designs, implementation procedures, test plans, and rollback plans for voice and UC solutions, and participate in peer reviews of designs produced by other engineers.
- Platform Engineering: Implement and integrate IP telephony, SIP trunking, and SBC platforms, including Cisco Unified Communications Manager, Cisco CUBE, AudioCodes Mediant, and Ribbon SBC, following established reference configurations and recommending improvements.
- Dial Plans and Routing: Design and implement enterprise dial plans, E.164 normalization, digit manipulation, route patterns, and carrier and PSTN interconnections.
- Cloud Voice Integration: Implement and support integrations with Microsoft Teams Phone (Direct Routing and Operator Connect), Webex Calling, and comparable cloud platforms.
- Technical Guidance: Mentor junior engineers through peer review of configurations and knowledge transfer, and recommend improvements to standards and solutions to the Team Lead.
- Vendor and Carrier Escalations: Work with manufacturers, carriers, and SIP service providers to resolve defects and interoperability issues, escalating to senior engineers and the Team Lead as needed.
Multi-Program Support- Multi-Contract Support: Provide voice engineering support to multiple DoD contracts, prioritizing technical work across programs with the Team Lead.
- Standardization: Apply and help maintain common voice architectures, STIG-compliant baselines, and SIP normalization standards across contracts and customers.
- Proposal Support: Provide technical input to modernization efforts and capture or proposal activities, including solution designs, bills of material, and level-of-effort estimates.
- Customer Engagement: Communicate technical status, risks, and recommendations to program managers and government customers.
Required Experience and Education- Education and Experience: Bachelor's degree and 8 or more years of relevant experience, or a Master's degree and 6 or more years, in VoIP, enterprise telephony, unified communications, network engineering, or a closely related discipline. Additional relevant experience and certifications may be considered in lieu of a degree.
- Clearance: U.S. citizenship and the ability to obtain and maintain a Secret clearance are required. Leidos will sponsor the clearance for the selected candidate; an active Secret clearance is preferred.
- DoD 8140/8570 Compliance: Ability to obtain an IAT Level II certification (e.g., CompTIA Security+ CE) within the period required by the contract.
- SIP Experience: Hands-on experience troubleshooting SIP call flows in packet captures (e.g., Wireshark) or platform traces, including reading SIP messages and basic SDP offer/answer to identify common call failures.
- STIG Compliance: Demonstrated experience performing DISA STIG compliance checks, completing STIG checklists, and remediating findings on voice, UC, or network infrastructure.
- Layer 2 and Layer 3 Networking: Solid working knowledge of enterprise switching and routing (VLANs, trunking, Spanning Tree, routing protocols, ACLs, NAT, and QoS), sufficient to troubleshoot voice issues at the network layer and work effectively with dedicated network teams. Senior-level network engineering experience is not required.
- Voice Platforms: Hands-on experience with at least one enterprise call-control platform (Cisco Unified Communications Manager, Microsoft Teams Phone, or comparable) and at least one enterprise SBC (Cisco CUBE, AudioCodes, Ribbon, or Oracle/Acme Packet).
- Communication: Ability to explain complex technical issues, risks, and recommendations clearly to engineers, customers, and program leadership.
Preferred Technical Proficiencies- Protocols: Working knowledge of SIP, SDP, RTP/RTCP, SRTP, TLS, H.323, MGCP, and ISDN/PRI, with familiarity with core SIP RFCs such as RFC 3261 and RFC 3264.
- Security Tooling: Experience with DISA STIG Viewer, SCAP Compliance Checker, Evaluate-STIG, ACAS/Tenable Nessus, and RMF artifacts (POA&Ms, SSPs).
- Transport: Familiarity with SD-WAN, MPLS, and carrier transport as they affect voice and video quality.
- Video and Collaboration: Familiarity with VTC and collaboration endpoints such as Cisco Room Series, Poly, and Microsoft Teams Rooms.
- Automation: Scripting experience with Python, PowerShell, or REST/AXL APIs to automate STIG checks, configuration audits, provisioning, or trace analysis.
- Mission Environments: Experience supporting large-scale, geographically distributed, highly available DoD or mission-critical voice networks.
Preferred Certifications and Qualifications- Cisco Certified Network Professional (CCNP) Collaboration.
- Cisco CCNA or equivalent networking certification.
- CompTIA Security+ CE or other DoD 8140 IAT Level II certification (if not already held).
- Current AudioCodes, Ribbon, or Microsoft Teams Voice certification.
NGEN
If you're looking for comfort, keep scrolling. At Leidos, we outthink, outbuild, and outpace the status quo - because the mission demands it. We're not hiring followers. We're recruiting the ones who disrupt, provoke, and refuse to fail. Step 10 is ancient history. We're already at step 30 - and moving faster than anyone else dares.
Original Posting:November 10, 2026
For U.S. Positions: While subject to change based on business needs, Leidos reasonably anticipates that this job requisition will remain open for at least 3 days with an anticipated close date of no earlier than 3 days after the original posting date as listed above.
Pay Range:Pay Range $107,900.00 - $195,050.00
The Leidos pay range for this job level is a general guideline only and not a guarantee of compensation or salary. Additional factors considered in extending an offer include (but are not limited to) responsibilities of the job, education, experience, knowledge, skills, and abilities, as well as internal equity, alignment with market data, applicable bargaining agreement (if any), or other law.
About LeidosLeidos is an industry and technology leader serving government and commercial customers with smarter, more efficient digital and mission innovations. Headquartered in Reston, Virginia, with 47,000 global employees, Leidos reported annual revenues of approximately $16.7 billion for the fiscal year ended January 3, 2025. For more information, visit www.Leidos.com.
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