Pi Radio Gateway

Inexpensive IP base internal and external voice communication system gateway for offshore/onshore, maritime and naval radio equipment.

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IP device that interface with commercial HF/VUHF radios for external communication. Interface with analog loud speaker for public address. Intercom, conference calls between analog, IP phones and computer voice terminals. Ideal for integrating into a SIP base system.

IP PABX allows inexpensive telephone system via IP which is widely implemented. In simplest form, this VoIP device/project can be connected to an existing local IP PABX telephone system using Session Initiation Protocol (SIP). The device analog ports can then be interface with radio audio TX/RX and PTT. The radio became a part of the telephone system for voice communication.



Inside the enclosure, the IP PABX Module is the telephone system implemented, using Asterisk for Raspberry Pi (  Switching Module is just LAN switch. Analog Telephone Adapter (ATA) Module is optional to connect old telephone, and IP phones can be connected direct on LAN switch. At this point, it is a local telephone system with local extension numbers configured in the IP PABX Module dial plan. The Radio Channel MPU are microprocessor which is configured with a softphone ( These microprocessor is connected with a USB sound interface MIC/SPK along with a 1:1 audio transformer (for isolation) as Audio Interface. The PTT Interface and PTT Switch module is a microprocessor and SPDT relay switch respectively, where the radio PTT is controlled via software. There is a software I developed based on a commercial softphone SDK. This software is installed on a windows PC/Laptop (with MIC/SPK) to use as voice terminal to make calls to radio.

Since Radio Channel MPU is configured with softphone, all endpoint (telephone, softphone) on this local telephone system can dial or make a call to this MPU which is interfaced with a radio, making a radio gateway possible.


 This software is the user interface as a voice terminal to dial or call the gateway, and IP phones. It is a fully functional SIP phone and configurable extension number and dial plan. I developed it using C# .NET base on a commercial software development kit (SDK). 

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Audio Interface

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  • 3 × IoT Pi microprocessor
  • 1 × IoT Relay module
  • 3 × Cheap USB sound card
  • 1 × 4 port LAN switch (PoE to power PI)
  • 1 × Soft Phone A custom software installed on windows type PC as voice terminal

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  • Mobile phone (via wifi) to radio gateway

    Sonny Supilanas5 days ago 0 comments

    I tested "Pi Radio Gateway" in a wireless local network using my android mobile phone for connecting to radio, it worked. Downloaded a SIP phone app (I tried random PlayStore app PortSip) on the mobile phone, configure SIP account on it and dialed-in to the radio gateway. Similar to my previous Logs Telephone to Radio, it use DTMF for controlling radio PTT. At this stage I can use simultaneously Laptop to Radio , telephone and mobile phone on a local network for radio communication via the "Pi Radio Gateway".

  • Telephone to Radio

    Sonny Supilanas6 days ago 0 comments

    Radio via Telephone

    I add this feature to communicate over the radio using telephone unit. I used an IP phone, with configured SIP account, connected on the local network. A telephone call to the "Pi radio gateway", where the radio is connected, allow voice communication between telephone and radio. Since telephone unit has only keypads, dual tone multi frequency (DTMF) is used to control the radio PTT (dial 1 for PTT on, dial 0 off).

    The "Pi Radio Gateway" is a multi-session device, allowing simultaneous voice communication to radio from telephone and computer.. Multi-users from telephone and computer can be dialed-in at the same time in a single radio, making this device scalable.

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  • 1
    Setting to work

    Instruction is available at my GitHub repository, and still "work in progress".

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