MaBell Bluetooth Gateway: Project Plan #
Bluetooth Phone Gateway for vintage telephone integration.
Project implemented in a separate repository.
- GitHub: https://github.com/cdeever/esp32-ma-bell-gateway
- Documentation: https://cdeever.github.io/esp32-ma-bell-gateway/
Roadmap item: MaBell Bluetooth Gateway
Legend: ✅ Complete | 🔄 In Progress | ⏳ Planned
How MaBell is built #
MaBell is one unit, built for one home, so it is prototyped in stages rather than through a manufacturing lifecycle. Each stage proves every functional section of the gateway before the next stage starts: call tones, ringing, hook detection, rotary and touch-tone (DTMF) detection, call audio, and the indicators. Dial tone, for example, is first heard on a speaker, then injected into a phone’s earpiece and judged for authenticity. Ringing is first an LED and an electronic ring on the speaker, then a real bell.
The gateway detects dialing; it never generates it. The phone, or a stand-in on the bench, makes the rotary pulses and DTMF tones. The gateway decodes them and asks the cell phone to dial over Bluetooth HFP.
Each stage is a version, on its own page. A version’s definition of done and its tasks are written when it becomes current; until then its page sketches its scope. The line interface for the circuit board, the AG1171 SLIC module or the discrete HC-5504B SLIC, is chosen at the end of v3, with what the prototypes taught, and recorded with the options considered in the project’s design docs.
Versions #
| Version | Goal | Status |
|---|---|---|
| v0: Foundation | Requirements, design and the first firmware: the base every prototype builds on | Done |
| v1: On the bench | Every functional section proven on a breadboard, with stand-ins for the phone | Current |
| v2: A low-voltage phone | A real telephone on a 5V loop | Next |
| v3: Line voltage and a real bell | A vintage rotary phone at line voltage; the board’s line interface chosen | Planned |
| v4: Boxed and installed | The gateway on its own circuit board, in an enclosure, installed at home | Planned |
Vision & Scope #
Restore full, authentic use of vintage analog telephones by bridging them to modern Bluetooth cell phones — preserving rotary dialing, ringing behavior, tones, and user experience.
In Scope
- Rotary dial pulse detection
- Authentic ring, dial tone, busy/reorder tones
- Bluetooth HFP call handling
- Use of original phone and ringer hardware
Out of Scope
- VoIP provider integration
- Multi-line PBX features
- Smartphone UI replacement
- Manufacturing and selling units: MaBell is built once, for one home
Later #
Ideas kept for after v4, or for whichever version needs them:
- The rarer tones (SIT, stutter dial tone, call waiting)
- Field diagnostics beyond the MQTT state and the event log