6 month contract with opportunity to extend to 12 months (within scope of IR35) 37 hours per week, hybrid working pattern Hays Technology are working in partnership with a large public sector organisation in Birmingham city centre to recruit a Senior VOIP Infrastructure Engineer on a temporary contract basis. Our client is seeking an accomplished VOIP Infrastructure Engineer to lead the design, delivery, and ongoing management of its enterprise voice and Unified Communications environment. As the technical authority for VOIP services, you will be responsible for ensuring a robust, secure, and scalable telephony infrastructure that underpins critical operations. The role requires a blend of technical expertise, project leadership, and stakeholder engagement. You will drive strategic migrations from legacy platforms to modern SIP/cloud-based solutions, manage complex integrations across the network infrastructure, and provide senior-level guidance to both peers and junior engineers. Key Responsibilities: Serve as the service owner for enterprise VOIP and Unified Communications platforms. Define and deliver the roadmap for VOIP technologies in alignment with the digital strategy. Act as the senior escalation point for all VOIP-related incidents and problems. Lead the design, implementation, and migration of enterprise telephony services (Cisco Call Manager, SIP/Cloud platforms). Manage the transition from ISDN-based services to SIP/cloud voice solutions, ensuring resilience, cost-effectiveness, and future scalability. Oversee the integration of VOIP with core network, data centre, and security infrastructures. Ensure high availability and optimal performance of VOIP services through proactive monitoring, capacity planning, and fault resolution. Develop and maintain disaster recovery strategies for voice systems, minimising downtime and ensuring business continuity. Produce and maintain high- and low-level documentation, operational procedures, Lead enterprise-wide voice infrastructure projects, from planning and procurement through to deployment and support. Collaborate with Estates, Facilities, and third-party vendors to deliver end-to-end solutions, including structured cabling and interconnects. Present technical designs to senior managers and stakeholders, ensuring understanding and alignment. Provide technical leadership and mentoring to infrastructure engineers, building skills and capability within the team. Share best practices in VOIP, networking, and Unified Communications, fostering continuous improvement. In order to apply, you must have the following skills & experience: Extensive experience with enterprise VOIP and Unified Communications platforms (Cisco Call Manager, SIP, Cloud Voice). In-depth knowledge of SIP, ISDN, PSTN, RTP/SRTP, and voice gateway technologies. Strong understanding of QoS, DHCP, DNS, and network dependencies impacting voice quality. Proven track record of migrating from legacy voice systems to modern SIP/Cloud solutions. Enterprise networking knowledge (Cisco, Aruba, Fortinet) and experience integrating voice across LAN/WAN and firewalls. Skilled in network and voice monitoring tools (SolarWinds, PRTG, Prime Infrastructure). Strong stakeholder management and vendor relationship skills. Ability to lead large-scale technical projects with minimal supervision. Qualifications & Certifications (Desirable): Cisco Certified Network Associate (CCNA Voice/Collaboration) Cisco Certified Network Professional (CCNP Collaboration) ITIL Foundation Certification Microsoft Teams Voice or other cloud telephony accreditation Degree in IT, Networking, or a related discipline (or equivalent professional experience) If you have the relevant experience and would like to apply, please submit your CV. Hays Specialist Recruitment Limited acts as an employment agency for permanent recruitment and employment business for the supply of temporary workers. By applying for this job you accept the T&C's, Privacy Policy and Disclaimers which can be found at hays.co.uk