Bare-metal Telephony Workbench
An open-source SIP VoIP desk phone built on Arch Linux ARM and Raspberry Pi hardware.
BTW Phone is a project to build a fully functional SIP desk phone from the ground up - running the Linux kernel on commodity hardware, with every layer of the stack open and documented.
Commercial VoIP phones run proprietary firmware. Hobbyist SIP projects are usually software-only or microcontroller-based. BTW Phone aims to be a real desk phone, running a real Linux distribution, with real SIP interoperability.
The name "BTW" stands for Bare-metal Telephony Workbench. If it also reminds you of something else, it does run Arch by the way.
v1 - Proof of Concept - In Progress
Building on a Raspberry Pi 3 Model B+ with Arch Linux ARM, pjsip (PJSUA2 Python bindings), a USB audio dongle, and a Waveshare 4.3" HDMI touchscreen. The goal: a working SIP phone call over Ethernet with a basic touch UI.
V2 targets a Raspberry Pi 4 with an I2S audio codec, 3D-printed enclosure, and TLS/SRTP encryption.