IP technology
Metropolitan Police case study: Migration to all-IP technology
How we helped the Metropolitan Police Service transfer its networks to all-IP technology
December 02, 2025
5 minutes
The Met relied on nearly 5,000 increasingly unreliable PSTN lines to keep critical services like 999, 111 and 101 calls uninterrupted. With the ageing systems causing more faults and downtime, and the PSTN network being switched off by 2027, an upgrade was essential.
With BT’s expertise, the Met Police was able to upgrade all their infrastructure to an IP Connect MPLS network, providing strong connectivity and security. It also has scalability built in, enabling growth for the future.
The Met was seamlessly migrated to the new all-IP system, protecting critical services and elevating network and voice operations.
To keep Greater London safe, the Metropolitan Police Service (Met) rely on secure, resilient communications. Their legacy Integrated Services Digital Network (ISDN) and analogue systems were ageing, rigid and becoming harder to support, making a modern upgrade essential. Even more so with the PSTN switch-off fast-approaching.
We partnered with the Met to deliver a fully digital, all-IP network, including Session Initiation Protocol (SIP) trunking, a modern voice core, and IP connectivity across hundreds of sites. Our role went beyond technology; we helped shape the business case, define technical requirements, and manage multiple projects simultaneously to ensure a smooth, coordinated transition.
The Met led the overall programme direction, while we acted as subject matter experts, supported by a team of dedicated project managers to keep everything on track. The result is a resilient, future-ready platform that supports day-to-day operations, and safeguards 999 and 111 services. This enables the Met to confidently focus on protecting Greater London.
The challenge
In 2018 the Met Police faced a high-stakes upgrade. Their legacy infrastructure at that time included:
- 68 analogue circuits and 23 Kilostream circuits.
- Over 200 Megastream circuits.
- ISDN circuits.
- EFM (Ethernet First Mile) connections across 168 sites.
- 4,743 PSTN lines across hundreds of locations.
Ensuring uninterrupted service for critical functions - such as emergency calls (999 and 111), lift phones, alarms, and remote agency sites - was paramount. Migrating these to all-IP solutions had to be seamless, despite the challenges posed by ageing infrastructure and ongoing operational pressures.
Ofcom’s Connected Nations 2024 report showed a 45% rise in PSTN incidents, underlining how fragile the network had become. More outages, more faults and more risks for the Met. In February 2025 the Met successfully moved their 999/101 call platforms from ISDN30 to IP telephony trunks.
The solution
Modernising the Met’s communications meant safely upgrading network, voice and other mission-critical systems across the force. From planning and technical design to phased deployment, our solutions tackled legacy complexity, safeguarded critical services and futureproofed the force’s infrastructure.
BT implemented an IP Connect MPLS network across all Met sites, building a strong, scalable foundation for their all-IP transformation. It enabled advanced trunking and modern voice services, empowering the Met to maintain seamless communication throughout the transition.
We provided comprehensive, actionable data on every line and circuit, including inbound call volumes, channel utilisation, real-time provisioning visibility, broadband, and Red Care usage. This visibility allowed the Met to prioritise, plan and track migrations accurately, reducing risk and ensuring nothing was missed.
We introduced soft-cease capability to suspend services temporarily without full disconnection, allowing quick restoration when needed. Four soft-cease batches were trialled, starting with 500 lines, scaling to approximately 1,000 between two pilots and two commercial runs.
This approach resulted in minimal reconnections, safely accelerated decommissioning and reduced false positives. It was so effective that the Met is now expanding soft-ceases to other critical or low-traffic lines.
"Openreach’s decision to retire ageing analogue systems required the Metropolitan Police to replace decades-old infrastructure. BT’s technical expertise enabled a full transformation, modernising services from fax to critical 999 voice connectivity, ensuring resilient, future-proof communications for essential public safety operations."
Ian Pountney
Director of Core Infrastructure, Digital Data and Technology, Metropolitan Police Service
The result
We safeguarded critical but unusual services, such as lift emergency phones and other specialist lines, using Pre-Digital Phone Lines (PDPL) and phased migrations. Around 20% are already complete, keeping systems fully operational.
We also designed and deployed a new voice core system, rolling it out in phases across London control rooms January-March 2025. This meant seamless migration of 999 and 111 calls via SIP trunks, removing reliance on older ISDN30 circuits.
We provided on-site support during cutovers and 24/7 monitoring for two weeks post-go-live at each control room, resulting in zero downtime during critical emergency migrations.
Over 1,500 legacy handsets were retired and replaced with Teams-integrated softphones. This gave staff more flexibility, simplified the voice estate and aligned day-today communications with modern, cloud-friendly tool.
Environmental & peripheral line upgrades:
- Replaced ageing yellow weatherproof phones with rugged 4G-enabled units. Around 30% are already live, equipping staff with dependable, high-performing tools.
- Migrated broadband lines for building management, HVAC systems and fuel pumps, working alongside the Met’s Property Services team to futureproof key building systems and critical infrastructure.
- Upgraded Red Care alarm lines to radio-based or secure broadband solutions, helping retire over 400 legacy lines safely and efficiently.
- Transitioned fuel depot systems from PSTN to modern all-IP platforms, keeping essential operations running smoothly.
- Identified and removed more than 50 legacy analogue phones, freeing up space and easing future maintenance.
Delivering a modern, resilient all-IP network, BT helped the Met keep critical services running, streamline daily operations and prepare for the future.
