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Yes—you can build a working 4G phone as a hobby prototype using a Raspberry Pi, an LTE modem, a touchscreen, audio parts, and portable power. A documented project completed a first version in 2024 with LTE internet, calls, SMS, and contacts. That demonstrates a viable build path, not guaranteed carrier compatibility or a dependable daily-use handset.
What a DIY 4G phone can—and cannot—prove
The OURS open-source Linux smartphone project documents a Raspberry Pi 3 B+ running Raspbian and a Waveshare 4G HAT based on the SIM7600 modem. The Pi communicates with the modem using AT commands. The project lists LTE internet, calls, SMS, contacts, a 4-inch 480 × 800 touchscreen, GPS, Wi-Fi, and Bluetooth audio as features.
Those are the project’s reported features, not independent test results. In particular, the documentation does not establish that the same modem variant and software will support voice over LTE (VoLTE) with a particular operator today. Cellular bands, SIM requirements, voice provisioning, and acceptance of devices vary by modem, carrier, and region. Confirm those details with the operator and the modem documentation before buying parts.
Choose a build route
| Route | Best suited to | Trade-offs |
|---|---|---|
| Recreate the OURS project architecture | A first prototype based on a documented Raspberry Pi, SIM7600 4G HAT, display, battery, and peripherals. | It is a useful starting point, but check current component availability and your carrier’s requirements. A project build does not establish reliability for daily use. |
| Prototype with a Compute Module IO board, then design a carrier board | Makers who want to integrate components and potentially reduce the final board size. | More work in custom PCB design, power, RF, mechanical integration, and compliance. Raspberry Pi describes the IO board as a rapid-prototyping platform and reference design for custom carrier boards; its current documentation covers CM4 and CM5. |
| Study the older Adafruit PiPhone guide | Learning how a phone-like build combines a Pi, display, cellular hardware, antenna, battery, converter, and headset. | The guide is a legacy reference, not evidence of current LTE or VoLTE compatibility. |
For the IO-board route, consult Raspberry Pi’s Compute Module hardware documentation. Its computer hardware documentation recommends CM4 or CM5 for new designs outside the SODIMM form factor.
#1 Best Overall
- SIM7670G LTE Cat-1/GNSS HAT, with Standard Pi 40PIN GPIO extension header, compatibe with Raspberry Pi series boards. Support Global Multi Band of LTE Cat-1---LTE Cat-1: Up To 5Mbps (Uplink) / Up To 10Mbps (Downlink)
- Supports Dial-up on Windows/Linux---Supports connecting to Windows PC, Raspberry Pi, or other Linux industrial devices via USB interface for LTE Cat-1 networking and extending USB ports
- Supports GNSS positioning---Supports GPS, GLONASS, Galileo, BeiDou positioning
- Support Waveshare.cloud ---provides tutorial and demo for quick start of smart IoT solutions, with large-screen Data Visualization display to meet various application scenarios
- Application Example---provides multiple networking demos with Waveshare.cloud, using the lightweight MQTT protocol to achieve data visualization service
Plan the hardware around the cellular modem
Compute board and software
The Raspberry Pi runs the interface and phone-side software; the modem handles the cellular connection. OURS used a Pi 3 B+ with Raspbian. If you choose a different board, check that its operating system, interfaces, physical connectors, and power input suit the display and modem you intend to use. A Compute Module IO board can help you prototype an integrated layout before committing to a custom carrier.
Modem, SIM, and antenna
The documented OURS setup uses a Waveshare 4G HAT containing a SIM7600 and sends AT commands from the Pi. Before selecting a HAT or module, verify the exact variant’s LTE bands against those used by your carrier, along with antenna requirements, SIM format and plan requirements, and support for the voice services you need. LTE data registration alone does not confirm that calls will work: ask whether the operator provisions VoLTE for that modem or device in your region.
Rank #2
- Raspberry Pi & Jetson Nano Compatibility: Features a standard 40PIN GPIO extension header, supporting Raspberry Pi series boards and Jetson Nano.
- Communication Support: Supports various communication protocols, including dial-up, telephone calls, SMS, TCP, UDP, DTMF, HTTP, FTP, and more.
- Positioning and Navigation: Supports multiple positioning systems such as GPS, BeiDou, Glonass, GALILEO, QZSS, and LBS base station positioning.
- USB and Debugging Features: Includes an onboard USB interface for testing AT commands and GPS data retrieval, along with a CP2102 USB to UART converter for serial debugging.
- Additional Features: Equipped with a SIM card slot (supporting 1.8V/3V SIM), audio jack and decoder for telephone calls, 2x LED indicators for monitoring status, voltage translator for 3.3V or 5V operation, and supports autobauding and AT command control (including SIM application toolkit).
Display and controls
OURS lists a 4-inch, 480 × 800 touchscreen. The Adafruit PiPhone guide uses a 2.8-inch PiTFT. These examples show the display category, not guaranteed compatibility with a current board. Check the display interface, driver support, connector placement, touch input, and how much room the screen leaves for controls and enclosure walls.
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Portable power
OURS describes two 3.6 V batteries converted to 5.1 V DC for the Pi. Adafruit’s guide lists a 1200 mAh LiPo battery and a DC-DC converter. Neither source establishes runtime for a new design. Select a battery and converter for the chosen board’s input requirements and the modem’s transmit-current demand; include suitable charging and protection circuitry, then measure the complete device’s power draw under realistic use.
Rank #3
- Connected via pogo pin or MicroUSB connector Dedicated pogo pin for Raspberry Pi Zero/Zero W MicroUSB connector for other Raspberry Pi boards or PC
- Incorporates SIM7600G-H global band 4G module, compatible with 2G/3G/4G network with global support. USB HUB connector for other Raspberry Pi boards or PC, providing USB extension and 4G network access
- Supports dial-up, telephone call, SMS, TCP, UDP, DTMF, HTTP, FTP, etc. Supports GPS, BeiDou, Glonass, LBS base station positioning
- SIM card slot, supports 1.8V/3V SIM card. Onboard audio jack and audio decoder for making telephone call
- 2x LED indicators, easy to monitor the operating status. Control via AT commands (3GPP TS 27.007, 27.005, and V.25TER command set)
Audio and enclosure
A usable phone needs a microphone and speaker or headset, user controls, an antenna, and an enclosure that accommodates them without obstructing the antenna. OURS lists Bluetooth audio and a 1 W onboard speaker; Adafruit’s guide includes a hands-free headset with microphone. These are component examples, not acoustic or durability test results. Plan antenna placement and access to charging, SIM, and controls at the enclosure stage rather than treating the case as an afterthought.
Build and test in stages
- Confirm the cellular service first. Identify the exact modem variant and check its bands, SIM requirements, and voice support with the operator in your region. Do not assume a modem that connects to LTE data will also place calls.
- Bring up the modem on the bench. Connect the HAT or module to the Pi according to its documentation, attach the required antenna, and test SIM recognition and network registration before adding a screen or enclosure. Use the modem’s supported AT-command interface to check the functions your project needs.
- Add the display and controls. Verify the screen and touch input with the chosen board and operating system, then build the interface around actual screen dimensions and connection points.
- Integrate audio and power. Test microphone and speaker or headset routing. Add the battery, converter, charger, and protection circuitry only after confirming board input and modem current needs; check for resets or unstable operation during cellular transmission.
- Test the complete prototype on your intended network. Separately verify calls, SMS, data, and any required VoLTE behavior. Check that the antenna and enclosure do not prevent reliable operation, and measure power consumption rather than estimating battery life from battery capacity alone.
Compliance and daily-use limits
Do not treat a Raspberry Pi compliance statement as approval of a finished phone. Raspberry Pi’s documentation describes its own products and specifies that its UL94-V0 note applies to its PCBs; it does not establish that a custom, assembled handset meets the requirements that apply to a finished radio product. Applicable rules depend on the build and geography. A hobby prototype should not be assumed to be certified or accepted for unrestricted commercial or everyday use.
Rank #4
- ✅Designed for Raspberry Pi 5, HAT+ standard design with onboard I2C EEPROM, and supports Raspberry Pi 40PIN GPIO stackable expansion. Extends 3x high-speed USB 3.2 Gen1 ports for connecting more peripherals
- ✅Onboard M.2(NGFF) Key B slot, supports SIM7600XX-M.2, SIM82XX and RM5XX series 4G/5G modules and is compatible with 3042/3052 packages. Onboard Type-C port for connecting to a PC for 4G/5G networking, debugging and firmware updating, or external power supply input
- ✅Onboard power monitoring chip for real-time measurement of voltage, current and power. Onboard SIM card slot for NANO-SIM card
- ✅Onboard Reset button, Power and Network indicators for easy debugging and monitoring the operating status. Comes with customized 5G-4IN1-PCB Antenna for neat wiring management, supports top or bottom installation
- ✅Reserved airflow vent and mounting holes for cooling fan to increase airflow and provide better heat dissipation
Before committing to a daily-use design, account for carrier provisioning, regional radio requirements, electrical and thermal safety, mechanical robustness, and the reliability of the operating system and phone software. The cited project guides do not establish current stock for every listed part, total cost, dimensions, signal performance, battery life, or suitability for daily use.
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