The concept of network slicing has been one of the standout features in 5G (no pun intended). It allows operators to offer logically isolated networks over shared infrastructure, each tailored for specific applications or services. These slices are identified using a combination of the Slice/Service Type (SST) and an optional Slice Differentiator (SD), together forming what is called a Single Network Slice Selection Assistance Information (S-NSSAI).

To ensure global interoperability and support for roaming scenarios, 3GPP standardises a set of SST values. These are intended to provide common ground across public land mobile networks for the most prevalent slice types. Over the course of different 3GPP releases, the list of standardised SST values has grown to reflect emerging use cases and evolving requirements.

The foundation was laid in Release 15, where the first three SST values were introduced. SST 1 represents enhanced Mobile Broadband (eMBB), suitable for high throughput services like video streaming, large file downloads and augmented reality. SST 2 refers to Ultra-Reliable and Low-Latency Communications (URLLC), designed for time-sensitive applications such as factory automation, remote surgery and smart grids. SST 3 is for Massive Internet of Things (mIoT – earlier referred to as mMTC), tailored for large-scale deployments of low-power sensors in use cases such as smart metering and logistics.

The first major extension came with Release 16, which introduced SST 4 for Vehicle-to-Everything (V2X) services. This slice type addresses the requirements of connected vehicles, particularly in terms of ultra low latency, high reliability and localised communication. It was the first time a vertical-specific slice type was defined.

With Release 17, the slicing framework was extended further to include SST 5, defined for High-Performance Machine-Type Communications (HMTC). This slice is aimed at industrial automation and use cases that require highly deterministic and reliable communication patterns between machines. It enhances the original URLLC profile by refining it for industrial-grade requirements.

Recognising the growing importance of immersive services, Release 18 added SST 6, defined for High Data Rate and Low Latency Communications (HDLLC). This slice targets extended reality, cloud gaming and other applications that simultaneously demand low delay and high bandwidth. It goes beyond what enhanced Mobile Broadband or URLLC individually offer by addressing the combination of both extremes. The documentation refers to this as being suitable for extended reality and media services, underlining the increasing focus on immersive technologies and their networking needs.

Finally, Release 19 introduced SST 7 for Guaranteed Bit Rate Streaming Services (GBRSS). This new slice supports services where continuous, guaranteed throughput is essential. It is particularly relevant for live broadcasting, high-definition streaming, or virtual presence applications where quality cannot degrade over time.

This gradual and deliberate expansion of standardised SSTs highlights how 5G is not a one-size-fits-all solution. Instead, it is a dynamic platform that adapts to the needs of different industries. As use cases grow more sophisticated and diverse, having standardised slice types helps ensure compatibility, simplify device and network configuration, and promote innovation.

It is also worth noting that these SST values are not mandatory for every operator to implement. A network can choose to support a subset based on its service strategy. For example, a public network may prioritise SSTs 1 and 3, while a private industrial deployment might focus on SST 5 or 7.

With slicing increasingly central to how 5G will be “monetised” and deployed, expect this list to keep growing in future releases. Each new SST tells a story about where the telecoms ecosystem is heading.

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