# Voice Intercom and VoIP

[中文]

## Introduction

The voice-intercom and VoIP solution runs pickup, 3A processing, and the call protocol on ESP32 / ESP32-S3, without a separate DSP. The path can be SIP/VoIP on a LAN or the internet, or a carrier number for real inbound and outbound calls. It supports full-duplex one-to-one calls and multi-party conferences. Adding a camera extends it to a video call.

Near-field intercom does not need long pickup range: one microphone plus an audio codec is enough. Conference or far-field products can use a 1-to-3-mic array.

            flowchart LR
        Mic["Microphone"]
        Afe["NS and AEC"]
        Sip["SIP or VoIP"]
        Spk["Speaker"]
        Mic --> Afe
        Afe --> Sip
        Sip --> Spk

## Applications

- Smart devices: hands-free calling inside a speaker, appliance, or voice door lock

- Care and emergency: one-button help terminal or care alarm, connecting to a care desk or a designated number

- Conference and field work: conference phone; hands-free terminals for riding or delivery

- Child care: voice calling on a story player or care device, optionally with video

## Features

- SIP/VoIP network calls, plus carrier-number dialing and answering

- Full-duplex audio with noise suppression (NS) and acoustic echo cancellation (AEC)

- One-to-one calls or multi-party conferences

- Near-field single microphone, or a 1-to-3-mic array

- Optional voice assistant or simple display (HMI)

## Hardware and software

A common SoC is ESP32-S3; use ESP32-S31 when classic Bluetooth is required. The audio front end is in ESP-SR. SIP and related protocols are in ESP Media Protocols. An example is adf_examples/protocols/voip.

## References

- ESP-SR audio front end

- ESP Media Protocols

- VoIP example

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