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BT and Ericsson

A direct evolution to cloud native

BT’s journey toward a 5G Core

This is the story about how BT in UK leaped directly from physical to cloud-native architecture on the journey toward a 5G Core. All while successfully maintaining and improving service quality during the migration.


Watch this video where Reza Rahnama, MD Mobile Networks at BT, shares insights and learnings from this cloud-native journey

BT’s cloud-native Evolved Packet Core (EPC), which includes support for 5G non-standalone (NSA), was launched in 2022. As of December 2022, millions of subscribers had been migrated.

Ericsson collaborated with BT throughout this cloud-native journey, completing the transformation without a single reported service interruption.

BT’s new core network – the dual-mode 5G Core – is designed to support 5G SA and the new services BT aims to launch over the coming years, from new network capabilities to network slicing and network exposure APIs.

Agile cloud-native operations have been a main driver and the new solution- includes software probes, firewalls and optimization tools, consolidated into the cloud-native user plane.

BT’s drivers for change

  • Cloud-native transformation while maintaining its reputation for network leadership in UK ​
  • Move from physical to cloud-native architecture delivering on additional capacity, efficiency, security compliance, regular software drops and automation  ​
  • Collapse multiple network capabilities to increase agility and scalability​
  • Take advantage of network exposure APIs and plan for 5G standalone services
woman with VR AI glasses
photo of Reza at BT

“As of December 2022, we had migrated millions of subscribers to our new network. Service quality is very important to us, so carrying out this migration without a single reported interruption to our customers' service was a huge achievement." 


Reza Rahnama
MD Mobile Networks


The solution

Ericsson enabled BT’s cloud-native transformation through the dual-mode 5G Core. This cloud-native solution combines EPC and 5G Core network functions into a common platform, supporting both 4G and 5G.

BT has millions of customers still using 4G, so having a single core that can cope with both was important. Within Ericsson’s Packet Core Gateway, as part of the dual-mode 5G Core, BT was able to consolidate a number of functions including firewall, software probes and network address translation (NAT), as well as utilize additional functions for TCP optimization.  

Delivering high-quality services is absolutely vital for BT. Using Ericsson Expert Analytics, together with the built-in software probes, made it possible to see exactly what was happening to each subscriber and to the network.

Ericsson solutions delpoyed in BT’s cloud-native core network:

Ericsson’s dual-mode 5G Core: Combining EPC and 5G Core network functions into a common cloud-native platform for efficient TCO and migration to 5G, including products such as:

  • Ericsson Packet Core Gateway with value added functions including traffic and video optimization, NAT and built-in software probes as well as Packet Core Firewall, powered by A10 Networks, for integrated user plane and security functions in a single CNF
  • Ericsson Packet Core Controller with access, session, mobility and gateway control functions and built-in software probes to support the new 5G use cases

Ericsson Expert Analytics and built-in software probes: A cloud-native solution that performs customer-centric monitoring and identifies and troubleshoots issues

Ericsson Automated Acceptance Tests: Performs automated testing during the software acceptance phase of the CI/CD pipeline

Ericsson Cloud Container Distribution: Manages and orchestrates all containerized applications

Ericsson Orchestrator: A product incorporating Cloud Manager and Evolved VNF Manager, providing end-to-end cloud orchestration capabilities

Ericsson Network Manager: Provides a uniform operational environment on a cloud-ready software platform, and delivers close to zero downtime during software upgrades

Network design and deployment services: Supporting BT to produce configuration files, initial testing and deployment so BT can further test features on an end-to-end basis

BT 5G Core solution diagram

The result: A successful transformation

  • A cloud-native dual-mode 5G Core. ​As of December 2022, millions of subscribers had been migrated to the cloud-native EPC, without a single reported service interruption​
  • Agile cloud-native operations, including software probes, integrated firewalls and optimization tools, consolidated into the cloud-native user plane​
  • A network open for innovation and new services via network exposure and APIs 

“I'm really excited about the future of this network, simply because it allows us to deploy and develop new services."

 - Reza Rahnama, MD Mobile Networks, BT


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