What Is a Softphone and How Does It Work?

A softphone is an app that lets you make and receive business calls on a laptop, PC, tablet or mobile instead of a physical desk phone. It connects to your phone system over the internet, using your normal business number and extension. Callers can't tell the difference. You'll need a softphone app, an internet connection and a headset or the device's built-in microphone and speaker.

If you're deciding between an app and a handset, our guide to softphone vs desk phone compares the two. This article explains what a softphone is and what's going on behind the screen.

How does a softphone work?

A softphone does the same job as a desk phone, but in software. When someone rings your number, your phone system sends the call over the internet to the app. The app rings, you answer, and your voice travels back the same way as data.

A few things make that work:

• Registration. The app logs in to your phone system with your extension details, so the system knows where to send your calls.
• Signalling. A protocol called SIP sets up, manages and ends each call. Our guide to analogue vs SIP vs VoIP explains how SIP fits in.
• Audio. Your voice is turned into small packets of data and sent across your internet connection, then rebuilt at the other end.
• Your headset. The app uses your headset or device audio to capture and play sound.

You don't need to understand any of that to use one. For you, it looks like an app with a dial pad, a contact list and call controls.

What can a softphone do?

A good business softphone does far more than make calls. Most can:

• Make and receive calls using your business number
• Transfer, hold, park and conference calls
• Show who's available and who's on a call (presence)
• Access voicemail and call history
• Send messages and, on many systems, start video meetings
• Click-to-call from a web page or your CRM

What you get depends on your phone system. Our 3CX guides show the day-to-day basics, including the mobile app, the Windows desktop app and the web client.

What do you need to use one?

• A phone system that supports softphones. Most modern hosted and SIP-based systems do, including Gamma Horizon and 3CX.
• A device. A laptop, PC, tablet or smartphone.
• A headset. You can use built-in audio, but a decent headset makes a real difference to call quality.
• A stable internet connection. Wi-Fi works, but a wired connection is steadier for people on calls all day.
• Login details. Usually a username, password or a QR code from your admin.

What are the benefits of a softphone?

• Calls follow you. Staff can answer from home, the office or on the move without giving out a personal number.
• Lower hardware cost. A headset is far cheaper than a handset, and there's no network port or power supply to provide.
• Quick to roll out. Adding a new starter is a login, not a delivery.
• Everything in one place. Calls, contacts and messages sit beside the tools people already use.

Our post on how VoIP is powering hybrid working shows how this works for teams split between home and office.

What are the downsides?

Softphones aren't right for every role, and it's worth being straight about that.

• They depend on the device. If the laptop freezes, restarts for an update or runs out of battery, your phone goes with it.
• Headset quality matters. A cheap headset makes the whole system sound poor.
• Missed calls are easier. A ringing app can get buried behind other windows, or a muted laptop won't ring at all.
• Not ideal for everyone. Reception, shop floors and shared spaces usually work better with a physical handset.

Does it matter which device you use?

Not much, as long as the app supports it. Most softphones come in three forms:

• Desktop app for Windows or Mac, best for people at a computer all day
• Mobile app for iOS and Android, best for travelling staff and out-of-hours cover
• Browser-based client, which needs no install and suits shared or temporary computers

Many people use two at once, for example the desktop app at work and the mobile app on the move. All of them ring when a call comes in, and whoever answers first takes it.

Do softphones affect call quality?

They can, but only if something around them is wrong. A softphone is just as capable as a desk phone. Poor quality almost always comes from a weak headset, congested Wi-Fi or a network that isn't prioritising voice traffic. Our guide to why VoIP calls break up covers the usual causes. Our blog guide to optimising Quality of Service (QoS) explains how to give voice calls priority on your network, and our guide to VoIP bandwidth requirements shows how much capacity you need.

Frequently asked questions

Is a softphone the same as a VoIP phone? Not quite. VoIP is the technology that carries calls over the internet. A softphone is one way to use it, as an app. A VoIP phone usually means a physical handset that does the same job.

Do I need a headset to use a softphone? No, but it's strongly recommended. Built-in laptop speakers and microphones pick up background noise and echo, and they make long calls tiring.

Can I use my own mobile as a softphone? Yes, with your phone system's mobile app. Calls use your business number, so you don't have to share your personal one. Check your company's device policy first.

Does a softphone use my mobile minutes? Not if it's connected to Wi-Fi. On mobile data, calls use a small amount of data rather than minutes. A single call typically needs around 100 Kbps.

Can I use a softphone and a desk phone on the same extension? Yes. Most systems let one extension register on several devices at once, so a call rings everywhere and the first to answer takes it.

Is a softphone secure? Yes, when it's set up properly. Use a strong password, keep the app updated and make sure staff can report a lost laptop or phone quickly so access can be removed.

A softphone is often the quickest, cheapest way to get your team calling from anywhere. Request a quote for independent advice on the right setup, or use our phone system finder to compare systems.