NEN Solution Engineering - Senior Voice Engineer

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 principal-level subject matter expert for enterprise voice and SIP signaling, with 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, 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.This position supports multiple DoD contracts and serves as a cross-program technical authority for voice engineering. As a Level T5 engineer, the incumbent will influence solutions that affect strategic goals and business results across those programs, recommend and develop technical standards that are reused from contract to contract, and guide the technical work of other engineers. The position will work closely with Transport Engineering, Network Operations, Cybersecurity, program leadership, customers, and vendor partners.Key ResponsibilitiesSIP Signaling and Advanced Call-Flow TroubleshootingSIP Dialog Analysis: Serve as the senior escalation point for complex voice incidents, analyzing complete SIP dialogs (INVITE, provisional and final responses, ACK, re-INVITE, UPDATE, PRACK, REFER, BYE) to isolate signaling failures across multi-hop call paths.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,