Background Mobile
VoIP Icon/// TELECOM · VOIP & WEBRTC

VoIP & WebRTC App Development

Voice and video calling built into your apps and browsers — SIP and WebRTC, calls to ordinary phone numbers, routing and recording — engineered for the networks and phones people actually use.

WhatsAppMessage on WhatsApp
VoIP and WebRTC App Development Architecture
SIP and WebRTCPhone network callingNative call screen
Routing and IVRCall quality

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/// INTRODUCTION

A VoIP demo works on office Wi-Fi. A VoIP product has to work on a patchy mobile connection, behind a corporate firewall, on a locked phone with the app closed, and when the user walks from Wi-Fi onto 4G mid-call.

Sodio provides VoIP software development and WebRTC development for companies building calling into their products and for providers building voice services — voice and video in apps and browsers, calls to the phone network, routing, recording and the compliance that comes with them.

Smartphone real-time video call interface

/// IS CUSTOM RIGHT FOR YOU?

When a Ready-Made Phone System Is Enough

If what you need is a business phone system for your own staff, buy one — established cloud phone systems handle it well. A VoIP development company earns its place when calling is part of the product you build.

A ready-made phone system fits when

  • Your staff need desk phones and a mobile app
  • Standard call features are enough
  • Calls go to and from ordinary phone numbers
  • You are buying a service

Custom VoIP fits when

  • Your customers need to call from inside your product
  • Calling has to fit your own workflow and data
  • Calls connect users, agents, devices and phone numbers together
  • You are building one — as a UCaaS, CPaaS or ISP voice provider

/// WHAT IT COVERS

What VoIP and WebRTC Development Covers

VoIP software development covers far more than connecting two people. These are the parts a production calling product needs.

Voice and video calling

Voice and video calling

Group calls and conferencing

Group calls and conferencing

Phone network calling

Phone network calling

Native mobile call experience

Native mobile call experience

Browser calling

Browser calling

Call routing and IVR

Call routing and IVR

Recording and transcription

Recording and transcription

Messaging and presence

Messaging and presence

Call quality monitoring

Call quality monitoring

Security and compliance

Security and compliance

/// WHAT HAPPENS IN A CALL

What Happens Between Tapping Call and Hanging Up

STAGE 1 - START

A user taps call

The app requests the call and checks the user is allowed to make it

STAGE 2 - SIGNAL

The other side is alerted

Signalling over SIP or WebRTC rings the recipient’s device, even if the app is closed

STAGE 3 - CONNECT

A network path is found

NAT traversal finds a route between the two devices, relaying through a server when needed

STAGE 4 - TALK

Audio and video flow

Encrypted media sent with a codec that adapts to the network

STAGE 5 - ROUTE

The call reaches its destination

Delivered to an app, a browser, a queue or an ordinary phone number

STAGE 6 - END

The call finishes

Call record, recording and quality measures saved

/// WHY CALLING IS HARD

Why Calling Is Harder Than It Looks

Incoming calls do not ring
Why it happensPhones close background apps to save battery
How it is handledPush notifications that wake the phone, and the native call screen on iOS and Android
Calls fail behind firewalls
Why it happensCorporate and home networks block direct connections
How it is handledNAT traversal, with relay servers when a direct path is impossible
Choppy or robotic audio
Why it happensJitter and packet loss on busy or weak networks
How it is handledCodecs that adapt to the network, jitter buffers and error correction
Calls drop when users move
Why it happensThe device’s address changes between Wi-Fi and mobile data
How it is handledAutomatic reconnection without ending the call
Echo and background noise
Why it happensSpeakers, rooms and cheap headsets
How it is handledEcho cancellation and noise suppression
Group calls overload connections
Why it happensEvery participant sending to every other
How it is handledA media server that forwards streams, with quality adjusted per participant

Works with Twilio, Vonage and Agora, SIP trunking providers, and open-source media servers such as Asterisk, FreeSWITCH and LiveKit.

Gradient

///AI IN CALLING

Where AI Helps Calling

AI is changing what a call can do after it ends — and, increasingly, while it is happening.

Every call transcribed and summarised, with action points, for users who need a record of what was agreed.

Background noise removed in real time, so a call from a busy street sounds like one from a quiet room.

For contact centres, answers and next steps suggested while the customer is still speaking.

/// COMPARE

Communications API, Open-Source Stack or Custom VoIP Solutions

Examples
Communications APITwilio, Vonage, Agora
Open-source stackAsterisk, FreeSWITCH, Kamailio, LiveKit
Fully customBuilt for your product
Time to launch
Communications APIFastest
Open-source stackModerate
Fully customLongest
Cost at scale
Communications APIPer-minute fees that grow with usage
Open-source stackInfrastructure and engineering
Fully customInfrastructure and engineering
Control and data location
Communications APILimited to what the provider offers
Open-source stackHigh
Fully customComplete
Engineering effort
Communications APILowest
Open-source stackSignificant
Fully customHighest
Best for
Communications APILaunching and most products
Open-source stackGrowing products with rising call costs
Fully customProviders and products at large scale

Most products should start on an API. We build on all three, and help you move between them when the numbers change.

/// COST AND TIMELINE

What Drives the Cost and Timeline

A working calling feature on real devices typically arrives within 30 days, with a production build in 90.

30 daysWorking calling feature on real devices
90 daysProduction build

The cost moves with six things: how many platforms it runs on — iOS, Android, web and desktop; whether calls reach the phone network; the size of group calls; recording and transcription; the compliance involved, from emergency calling to recording consent and data location; and how many calls must run at once.

/// /// FAQ

Frequently Asked Questions

Decide first where calls need to go — only between your own users, or to ordinary phone numbers as well — and which devices they must work on. Then choose whether to build on a communications API or run your own calling infrastructure, build the calling experience on each platform, handle the difficult parts such as incoming calls on locked phones and calls through firewalls, and test on real networks rather than office Wi-Fi.

WebRTC is the open standard that lets browsers and apps make real-time voice and video calls without plugins. You need WebRTC development whenever calls happen inside a web page or app, rather than on a traditional phone system. It is often combined with SIP, the standard telephone networks use, so app users can reach ordinary phone numbers.

Most products should start on a communications API such as Twilio, Vonage or Agora: it is the fastest way to launch. Running your own stack starts to make sense when per-minute fees grow large, when data has to stay in a particular country, or when you need control the API does not give you. We will say which applies to you.

Because phones close apps running in the background to save battery. An incoming call has to wake the phone through a special push notification and hand the call to the phone’s own calling screen — CallKit on iOS and ConnectionService on Android. Getting this right is one of the most common gaps in VoIP apps, and one of the first things we build.

It depends on what the service does and where. Services that connect to the phone network usually carry emergency calling obligations — in the US including rules on sending a caller’s location with 911 calls, and in the UK access to 999 and 112. Recording calls requires consent, and the rules differ between US states and between countries. In the US, outbound calls to the phone network must carry verified caller ID under STIR/SHAKEN.

On every call, not by sampling. Each call records its audio quality score, jitter, packet loss and delay, so problems can be traced to a network, a device or a region, and fixed before users give up on the app.

/// RELATED SERVICES

Related Industries and Services

Routes where scope overlaps with VoIP and WebRTC.

/// GET STARTED

Start With the Call Your Users Need to Make

Tell us who needs to call whom, on which devices, and whether calls must reach ordinary phone numbers. We will prepare a free solution architecture — including whether to build on an API or run your own stack.

Contact Us