Senior Telephony Engineer - Systems Integrator

Ready for a contract role focused on delivering world‑class technology solutions?

Join a technology innovator specialising in information technology consultancy and digital services that empower businesses to modernise, optimise, and secure their operations. They provide end‑to‑end IT expertise spanning digital transformation, data and analytics, cybersecurity, managed services, cloud and platform support, and software development for organisations around the world. The role will provide technical leadership across discovery, architecture design, migration planning, and delivery oversight, ensuring business-critical voice services remain resilient throughout the transition.

Step into a role where your work drives real change, strengthens digital capabilities, and places you at the forefront of modern IT solutions and innovation!

Key Responsibilities:

• Estate Discovery & Risk Baseline:
  • Conduct discovery of the existing PSTN/ISDN telephony estate including lines, circuits, PBXs, gateways, and dependent services.
  • Identify operational and service continuity risks associated with Legacy telephony infrastructure.
  • Establish a baseline view of the current telephony environment and supporting infrastructure.
• Future State Architecture Definition:
  • Design future-state telephony architecture leveraging SIP trunking and VoIP technologies.
  • Define Session Border Controller (SBC) strategy, failover design, and carrier connectivity.
  • Ensure solutions meet resilience, scalability, and operational requirements.
  • Provide architecture input for Microsoft Teams telephony integrations where required.
• Migration & Remediation Planning:
  • Develop migration strategies and phased transition plans from PSTN/ISDN to SIP-based services.
  • Identify and plan remediation for Legacy or unsupported telephony components.
  • Manage carrier porting processes, numbering strategy, and service cutovers.
  • Work closely with network teams to ensure readiness across QoS, VLANs, routing, and resilience.
• Delivery Oversight & Technical Assurance:
  • Provide technical oversight during migration delivery.
  • Validate solution designs, deployment plans, and carrier integration.
  • Ensure continuity and stability of telephony services throughout migration activities.
  • Support troubleshooting and resolution of complex telephony issues.
• Documentation & Knowledge Transfer
  • Produce clear technical documentation and architecture artefacts.
  • Create operational runbooks and migration playbooks.
  • Deliver knowledge transfer to internal infrastructure and support teams.

Required Experience & Skills:

• Proven experience working on PSTN/ISDN retirement programmes.
• Strong knowledge of SIP trunking, Session Border Controllers (SBCs), and carrier porting processes.
• Deep understanding of VoIP networking, including QoS, VLANs, failover design, and SBC deployment.
• Experience implementing Microsoft Teams Direct Routing or Operator Connect.
• Experience supporting emergency or mission-critical telephony environments.
• Strong troubleshooting skills across enterprise voice and network infrastructure.

Desirable Experience:

• Experience working in large enterprise or public sector telephony environments.
• Familiarity with hybrid voice environments (on-prem PBX integrated with cloud telephony).
• Experience working with network, infrastructure, and security teams in complex environments.

Contract Details:

• Duration: 12-month contract
• Location: Remote/UK Wide site travel (when needed)
• Start Date: ASAP

Salary:

• £400 Per Day - £450 Per Day (Outside IR35)