Teltonika Calyx 4G and 5G RedCap HAT+ A New Path to Cellular Raspberry Pi IoT

Teltonika Calyx Brings 4G, 5G, and 5G RedCap to Raspberry Pi Builders

If you work with Raspberry Pi or other single board computers, you have probably used USB dongles, external routers, or homegrown carrier boards to bring cellular connectivity into your projects. That works, but it is not always pretty, repeatable, or industrial.

Teltonika is aiming directly at that gap with the launch of Calyx, their first embedded systems product line. Calyx is a family of cellular Raspberry Pi HAT+ boards that bring proven Teltonika modem technology right onto the Pi, ready for real world IoT and edge deployments.

In this post we will walk through what Calyx is, why it matters, and how you might use it in your next project or product.

The big picture: Embedded systems and the Raspberry Pi ecosystem

The embedded systems market is already huge and still growing. Global estimates put the market over 100 billion US dollars in 2025 and project it to reach more than 169 billion US dollars by 2030. A lot of that growth is driven by connected devices that have to live in harsh environments, stay online without IT support, and still be cost effective.

Single board computers, especially Raspberry Pi, have played a big role in this shift:

• Raspberry Pi is used by nearly 40 percent of developers, well ahead of Arduino and many other platforms.
• More than 7 million Raspberry Pi boards ship every year, and over 71 million units have been sold overall.
• Raspberry Pi has evolved from an educational tool into a standard platform for embedded prototyping, IoT development, and even small scale production systems.

What made Raspberry Pi so powerful is not just the board itself, but the HAT ecosystem.

Quick primer: HAT and HAT+ for Raspberry Pi

HATs (Hardware Attached on Top) are expansion boards that plug onto the 40 pin GPIO header of a Raspberry Pi. Instead of designing your own PCB or soldering components, you can stack a HAT and instantly add new capabilities, such as:

• Extra I/O
• Sensors and control interfaces
• Communication modules like LoRa, WiFi, or cellular

HATs turn Raspberry Pi into a modular prototyping platform. The best part is that a setup you build on your desk can often evolve directly into a production ready device, with minimal redesign.

With Raspberry Pi 5, the HAT+ standard arrived, which adds:

• Extended GPIO signaling
• Easier board recognition by the Pi
• Better power negotiation
• Improved performance when multiple HATs are used together

Teltonika Calyx is built to that HAT+ standard and designed from the start as a cellular add on that is ready for real deployments, not just labs.

Meet Teltonika Calyx: 4G, 5G, and 5G RedCap

Calyx is Teltonika’s first embedded systems product line, and it consists of three Raspberry Pi HAT+ variants:

• Calyx 4G CAT4
• Calyx 5G
• Calyx 5G RedCap

All three are built around the same core ideas:

• Raspberry Pi focused design
  • Credit card sized footprint that matches Raspberry Pi dimensions
  • Only the antenna connectors extend past the board outline
• Industrial temperature support
  • Rated from -40°C to +75°C, which means they are ready for factory floors, outdoor cabinets, and utility sites
• Flexible SIM options
  • Single nano SIM slot as standard
  • eSIM support available via customized order codes, with GPIO based control for SIM switching on those variants
• Clean electrical and software integration
  • USB Type C port for both data and power
  • Modems controlled by AT commands and managed from the Raspberry Pi via modem manager
  • GPIO signals for power up, sleep restoration, and SIM handling
• Audio and voice capabilities
  • PCM support for audio between the Raspberry Pi and the modem
  • All models support VoLTE, with voice calls routable via PCM over USB or dedicated pins
• Backwards compatibility
  • Designed for Raspberry Pi 5 and HAT+
  • Backwards compatible with older Raspberry Pi boards
  • Potential compatibility with other single board computers that share a similar GPIO layout

One important design note: Calyx does not provide a throughput GPIO header. It can be used in a multi HAT stack, but it has to live at the top of the stack.

What is special about the 5G and 5G RedCap versions

From a radio perspective, there are some key differences between the three Calyx variants:

• 4G CAT4 Calyx
  • Uses 2×2 MIMO
  • Targets mainstream LTE applications where 4G is more than enough
• 5G Calyx
  • Uses 4×4 MIMO for higher performance
  • Supports carrier aggregation in both 4G and 5G networks
  • Intended for bandwidth hungry or latency sensitive applications where full 5G makes sense
• 5G RedCap Calyx
  • Uses 2×2 MIMO
  • Based on 5G RedCap (Reduced Capability) which is designed for mid range IoT devices that need better performance and efficiency than LTE, without the full complexity and cost of high end 5G user equipment
  • According to Teltonika, there is no direct competitor in the market today for a 5G RedCap Raspberry Pi HAT

From a regulatory perspective:

• The North American 5G Calyx will be FCC certified out of the box, which simplifies deployments in the United States.
• The global 5G RedCap Calyx modem will also receive FCC certification for North American use.
• A specific 4G North American Calyx variant is not currently planned, but Teltonika indicated that market feedback could influence that.

Note that band N79 is not supported in current 5G Calyx generations. That would require a new modem generation based on 3GPP Release 17.

Another nice touch: the same modem families used in Calyx appear in Teltonika’s mobile routers. That means you are working with radio technology that already has a strong track record in the field.

Where Calyx fits: Practical use cases

Because Calyx combines industrial temperature ratings, direct Raspberry Pi integration, and proven Teltonika modems, it fits very naturally into a number of applications.

Some of the use cases Teltonika highlighted align closely with what we see 5Gstore customers building:

1. Factory and utility edge connectivity
   In many plants or utility environments, the IT network is hardened, segmented, or simply not available to OT teams. A Calyx equipped Raspberry Pi can give your machine, PLC, or telemetry system a secure cellular backhaul that does not depend on getting an IT firewall rule approved.
2. Digital signage and interactive displays
   Think shopping mall wayfinding screens, in store interactive kiosks, and large outdoor LED signs. With Calyx, your signage controller can live inside the display enclosure and maintain its own cellular connection for content updates and monitoring.
3. Remote monitoring for infrastructure
   Pumping stations, water towers, and remote cabinets often sit where wired internet is not economical. A Pi plus Calyx can collect sensor data, run local logic, and push updates through the cellular network.
4. Industrial telemetry and SCADA style systems
   Warehouses and factories often need to track inventory levels, equipment status, and alarms. A cellular connected SBC can poll local devices, buffer data, and report upstream without depending on the corporate LAN.
5. SMS and voice gateways
   Since Calyx supports VoLTE and PCM audio, it can form the radio side of an SMS or voice gateway solution. Developers can build custom alerting or voice applications that tie directly into mobile networks.
6. Edge AI systems
   For teams running AI inference at the edge, Raspberry Pi and similar SBCs often act as the host for models that process camera feeds or sensor data. Calyx gives those systems a mobile pipe back to the cloud, even when no wired or WiFi infrastructure is available.

Competitive landscape and why Calyx is interesting

In the 4G world, there are many options:

• Direct cellular HATs
• Carrier boards that accept M.2 modems
• Various USB solutions

Here, Teltonika’s advantage is less about being the only option and more about:

• Their established global distribution channel
• Strong supply chain
• Reputation as a quality manufacturer of industrial routers and IoT hardware

In the 5G space, things thin out quickly:

• Many competitors rely on separate carrier boards plus M.2 modems
• Integrators have to assemble multiple pieces and handle antenna integration themselves
• Fewer solutions offer a tidy, out of the box HAT form factor with industrial temperature specs

That is where Calyx 5G stands out. It gives developers a ready made 5G HAT that drops onto a Raspberry Pi and behaves like a mobile broadband modem in the Pi’s modem manager, needing little more than a single CLI command to fully automate connectivity.

For 5G RedCap, Teltonika is even further ahead. At the time of the announcement, Teltonika indicated that they did not see any direct competition for a RedCap based Raspberry Pi HAT. If you are designing mid range IoT devices that will ship in volume over the next several years, RedCap on a production ready HAT is a very compelling starting point.

Teltonika also confirmed that they do not plan to sell empty modem boards or separate carrier boards for third party modules. Calyx is positioned as an integrated, Teltonika controlled solution rather than a mix and match hardware kit.

Management, RMS, and integrations

Out of the box, Calyx appears on the Raspberry Pi as a mobile broadband modem managed through the standard modem manager stack. That allows for scripting and automation using common Linux tools.

Teltonika’s Remote Management System (RMS) is not yet available for Calyx, but Teltonika shared that RMS support was a recurring request during the webinar. The most likely path is that RMS support would arrive first for the 5G Calyx version, then potentially extend to other models based on demand.

Although Calyx is built for Raspberry Pi, Teltonika noted that it can also operate with other single board computers, as long as the GPIO pinout and electrical behavior match. There are hundreds of Pi compatible SBCs in the market, each with small differences, so field testing is important if you plan to deploy Calyx on a non Pi platform.

Two Calyx units can technically be used on the same SBC at once via USB connections. However, in that scenario power delivery must be carefully designed so that the USB side handles the energy budget rather than relying solely on GPIO power pins.

Firmware updates will be available across the Calyx family, although final upgrade tooling and procedures are still being defined.

What this means for 5Gstore customers

For years, many 5Gstore customers have built solutions around external routers and modems. That is still a great pattern for a lot of deployments. With Teltonika Calyx, another pattern becomes practical:

• Use Raspberry Pi or another SBC as the brain
• Drop a Calyx HAT+ on top when you need reliable, industrial cellular connectivity
• Stay in a familiar development environment while moving much closer to a production ready embedded design

If you are designing digital signage, industrial telemetry, edge AI, or remote monitoring systems and want to explore how Calyx might fit into your roadmap, the 5Gstore team can help you think through:

• Which Calyx variant makes sense for your use case
• How to plan for antennas, SIM or eSIM, and carrier selection
• When it is time to move from a prototype on your bench to a repeatable production build

As Teltonika expands Calyx and potentially adds RMS support, the gap between traditional industrial routers and embedded cellular modules will continue to shrink. That is good news for developers, integrators, and anyone trying to bring connected devices to market faster and with less friction.