OpenCellPhone

An open hardware + software cell phone using the global GSM network.

Arduino-based and fully open-source, OpenCellPhone is a DIY mobile phone project that runs on AT commands, handles SMS/calls, and supports a touch-based interface with a custom-built GUI.

2014/15 Hackaday Quarterfinalist

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🚀 Features

• Full support for SMS send/receive
• Touch-based dial pad and passcode lock screen
• Call handling (dial, receive, hang up)
• Basic notifications, call timer, and incoming caller display
• Real-time clock display from GSM module (AT+CCLK)
• Visual signal strength display (AT+CSQ)
• Low-power display handling with timeout/dim/sleep modes

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🧠 Planned and Future Features

Needed Features

• Lookup table for pixel width for screen formatting
• Sent SMS display and storage
• Secondary storage for messages
• Emergency calling from passcode screen
• In-call volume adjustment
• Call waiting support (AT+CHLD)
• Missed call tracking
• SMS management (delete, reorder, store)
• Signal strength meter
• Re-dial last number (ATDL)
• Notification screen with better intelligence

Future Features

• Bluetooth & FM Radio
• Contact List / Phone Book
• Adjustable screen brightness
• Airplane mode (AT+CFUN)
• SMS sorting by sender/contact
• Swipe gestures for UI
• MMS view/send, image handling
• Light sensor and auto-brightness
• MP3/audio playback
• GPS & accelerometer
• Display output
• Web browser
• Ringtones
• Configurable settings via touch UI

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📋 SIM Limitations

• SIM card storage is limited to 30 SMS messages

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⚙️ Build Info

Architecture

• Built with Arduino IDE
• Written in C/C++ with low-level serial AT command integration
• GUI rendered using RA8875 touchscreen driver
• Touchscreen and backlight managed through PWM and pin control

Libraries & Tools

• RA8875 display/touch driver
• Standard Serial, Wire, and SPI Arduino libs
• Custom utility functions for character buffering and cursor logic

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🧪 AT Command References

Command	Description
ATD*99#	Dial Access Point
AT+CGDCONT=1,"IP","access.point.name"	Defines PDP context
AT+VRX	Record in-call audio
AT+COPS=?	List available networks
AT+CSQ	Check signal strength
ATDL	Redial last number
AT+CHLD	Call waiting options

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🧰 Development Setup

Folder Structure

/PrototypePhone
│
├── /lib                # Optional custom libraries
├── PrototypePhone.ino  # main file