Ingénieur Expert Communications Unifiées (UC Engineer / UC Expert) H/F (IT) / Freelance

General Context / Mission

Design, validate, and industrialize hybrid unified communications architectures (on-premises / cloud) for multi-site and international environments. Act as a technical referent for Microsoft Teams Voice, M365 telephony, and collaboration services to ensure the availability, security, and scalability of deployed UC solutions.

Main Responsibilities

Architecture Design and Validation

• Define hybrid UC technical architectures (SBC, session routing, trunking, cloud telephony / PSTN, survivability).
• Write architecture documents, network diagrams, and technical specifications.
• Conduct Proofs of Concept (PoC) and integration tests.

Technical Project Management

• Technically lead complex UC projects (deployments, migrations to Teams Voice, integration with third-party systems).
• Coordinate internal teams and service providers (network, security, telephony, SIP trunk providers).
• Ensure tracking of schedule, quality, and technical budgets (workload estimation, deliverable validation).

Microsoft Teams Voice & M365 Telephony Technical Referent

• Configure and administer Teams Phone, Direct Routing, Operator Connect, and PSTN routing mechanisms.
• Manage call policies, numbering, voice routing, SBCs, and interconnection.
• Ensure compliance with Microsoft best practices and M365 roadmap.

Standards Definition & Best Practices

• Write and maintain standards, implementation guides, runbooks, and checklists.
• Contribute to the UC roadmap (prioritization, technology choices, migration).

Advanced Support & Operations

• Provide L3 support and escalation for major voice/collaboration incidents.
• Implement monitoring, alerting, capacity planning, and performance baselines procedures.
• Participate in post-incident reviews and propose improvement plans.

Change Management & Training

• Produce training materials, guide key users and operational teams.
• Conduct adoption actions (workshops, upskilling sessions, FAQs).

Candidate Profile

• Expertise in Microsoft Teams Voice / Microsoft 365 (Direct Routing, Operator Connect, Calling Policies).
• Knowledge of SBCs (Session Border Controllers) and SIP, RTP, TLS, SRTP protocols.
• Mastery of hybrid voice architectures (on-premises PBX to cloud migration).
• Network knowledge (QoS, VLANs, routing, firewall/NAT implications for voice) and security applied to voice.
• Experience in integration with third-party systems (PBX, contact center, CRM).
• Voice supervision/monitoring tools and call quality analysis (CQD, MOS).
• Good automation practices (PowerShell/Graph API for M365) and knowledge of Teams APIs.

Additional Skills Appreciated

• International / multi-site experience and service provider management.
• Knowledge of UCaaS, CPaaS, WebRTC, virtualized SBCs.
• Familiarity with digital transformation and change management projects.

Qualifications & Experience

• Bachelor's degree or equivalent experience in IT, networks, or telecommunications.
• 5+ years of experience in unified communications, ideally in a multinational environment.
• Proven experience as a technical lead for Teams Voice and telephony migrations.

Recommended Certifications

• Microsoft Certified: Teams Administrator Associate (or M365 equivalent).
• Network / security certifications (e.g., CCNA / CompTIA Network+ / CISSP depending on context).
• SBC / SIP trunk provider certifications (depending on chosen equipment).