The Challenges and Opportunities of 5G Roaming

Some argue that 5G standalone networks are designed primarily for machines rather than humans, and there's some validity in this claim. For our everyday needs, LTE networks are more than sufficient. However, 5G introduces entirely new realms beyond human experience, with terabytes of data (big data) and near-instantaneous low latencies (milliseconds).

As we navigate the transformations brought by Industry 4.0—comprising digital connectivity and sensors, digital engineering, and digital operations—it becomes evident that the international architecture of collaborative telecommunications networks must evolve to meet these challenges. Moreover, in an era where businesses transcend borders due to globalization, adopting smart 5G roaming services becomes imperative to address the demands of the next industrial revolution.

What is roaming?

For many, data roaming has traditionally meant higher costs for using voice, text and data services outside their home country. This is because a tablet, phone or other device connects to the local network wherever it happens to be in the world. With each evolution of mobile technology, the complexity of roaming solutions grew. This resulted in half-measures such as forcing devices to switch to a previous generation (N-1)G when the current generation (N) couldn't handle it. This approach is incongruent with the vision of a new industry built on digital data exchange.

Due to gradual developments over many years, current roaming solutions are primarily tailored to voice calls and basic data transmission. This state of affairs is clearly inadequate for large-scale industrial applications.

Why is 5G roaming needed?

Roaming agreements that have already been established between 5G networks demonstrate the readiness of the market to leverage the full potential of 5G technology. Whether you are on your home network or abroad, 5G roaming promises faster speeds, reduced latency, enhanced device connectivity, and improved security.

The need for 5G roaming is closely tied to the lifecycle of telecommunications networks. The deployment of 5G networks involves reclaiming radio access network (RAN) frequencies through a process known as refarming. This leads to the gradual phasing out of 2G and especially 3G networks. As 3G networks are retired, it becomes imperative to implement Voice over LTE (VoLTE) solutions swiftly in 4G networks. This, in turn, necessitates adjustments to roaming agreements. Customers increasingly demand access to advanced 5G services even when outside their home country. Notably, the implementation of 5G does not provide a fallback option to previous mobile network generations, such as 2G or 3G, especially for voice calls.

However, the most compelling reason for implementing 5G roaming is to pave the way for the global provision of Internet of Things (IoT) services—often referred to as 5G Reduced Capability or ”RedCap”. This is tailored for mid-tier use cases, offering a balanced mix of capabilities in terms of throughput, battery life, device complexity, and device density. These features make it cost-effective for powering a wide range of use cases that don't always require the high-performance capabilities of standard 5G technology. It's important to note that, for RedCap to function optimally, it relies on 5G standalone (SA).

To enable Industry 4.0 applications worldwide, 5G SA roaming is a fundamental requirement. It's a seemingly straightforward necessity in our journey towards realizing the potential of next-generation technologies.

How does 5G roaming differ from its predecessors?

In the realm of 5G technology, roaming operations will take place on a peer-to-peer basis facilitated by the use of security edge protection proxy (SEPP) nodes. However, these operations will now employ a new connectivity protocol via HTTP/2 over TLS. IPX operators, who often provide wholesale roaming platform services, have been promoting their solutions, including hosted SEPP services, for some time. Furthermore, prominent 'carrier of carriers' operators are already advertising 5G standalone and non-standalone 5G international roaming solutions.

For mobile operators, a significant challenge lies in the swift integration of the SEPP node into the 5G SA network. This task is not trivial, as not all suppliers are prepared to provide SEPP nodes or collaborate with those from other suppliers. As a result, there are offers of hosted SEPP functions from major transit players.

The SEPP network function as a non-transparent proxy node, tasked with safeguarding application layer control plane messages exchanged between network functions located in distinct public land mobile networks (PLMNs). The SEPP plays a crucial role in ensuring the security of Internet connections between 5G networks and maintaining data integrity throughout the process of 5G roaming message exchange. The SEPP's specifications are well-defined in ETSI/3GPP recommendations, with an essential reference being TS 33.501. From an inventory perspective, TS 28.541 is particularly significant.

How can Comarch help?

Comarch is perfectly placed to serve customers in the realm of 4G/5G roaming, including Diameter signalling and IR.21 roaming documents. Our solutions have been successfully implemented for a “carrier of carriers” class operator. Additionally, thanks to a project undertaken in the Far East, we have already established the inventory of the 5G core components. These include network functions modelled in accordance with 3GPP/ETSI 28.541 standards, encompassing elements such as SEPP and UPF (user plane function), as well as HTTP/2 Nxx trails, such as N32 and N9.

In the 5G standalone (SA) environment, we offer automation for a range of classic OSS tasks, including:

  • Inventory management of SEPP objects, with data sourced via auto-discovery and reconciliation, which even includes REST API event-based methods
  • Inventory and visualization of network connectivity for HTTP/2 connections that converge in SEPP, covering trails such as N.32f and N32c
  • Planning and provisioning of objects within the inventory database
  • Planning and provisioning of roaming relations
  • Maintenance and tracking of IR.21 documents for mobile network operators (MNOs)

These capabilities empower us to deliver efficient and streamlined solutions for 5G SA environments.


Tomasz Balcerak
Tomasz Balcerak
Mobile Core Product Manager

Tomasz Balcerak holds a Master's degree in Telecommunication Engineering from The Silesia University of Technology, and gained further expertise by completing Management of Telco Networks Postgraduate Studies at the National Institute of Telecommunication. With nearly three decades of experience in the telecommunications industry, his career has evolved from a telco traffic engineer to roles as an SS7/Diameter signalling expert. Tomasz is currently a Mobile Core Product Manager at Comarch Telecommunication OSS Business Unit, focusing on implementing innovative 5G core inventory solutions.

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