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CallFactory UK
Linphone · open source · Windows, macOS, Linux, iOS, Android

We did not build a softphone. We ship the one Orange, BT and Swisscom use.

Most providers put their own name on an app and hope you never compare it to a real one. We did not write ours, because writing a good softphone is a twenty-year specialism and we are a telecoms operator, not an app studio. Instead we supply Linphone — built in France by Belledonne Communications since 2001, fully open source, and already carrying calls for some of the largest operators in Europe. CallFactory is listed on their client page alongside them.

Get your number Where not to use it
  • Not home-brew a specialist’s product, maintained by a dedicated team, not a side project
  • Open source inspect what you are installing on your own equipment, line by line
  • Five platforms Windows, macOS, Linux, iOS and Android from the same project
  • Licence, not seat tied to a serial number, so it moves when people do

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Looking for an app to make calls? We deliver the best: Linphone. Open source, secure, and developed in France since 2001. Not a self-built app like you see with many providers, but an actively developed and maintained app. Linphone works not only on your mobile but also on your computer — really handy if you want to use your computer as a business phone.

The app connects to our platform over the internet using the VoIP credentials from your dashboard. As soon as someone calls your number, the app rings just like a desk phone; you see who’s calling and pick up, all from your screen.

Linphone is used by major operators like Orange, British Telecom and Swisscom. It works on Windows, Mac, Linux, iOS and Android.

A softphone is at its best on the desktop. The app stays open, holds its connection and rings reliably, and with a headset your hands stay free to type during the call.

On mobile there’s one thing to know. Because it’s an app, the operating system can close it in the background, so you might miss a call; if you want to be sure to receive every call on your mobile, use our fixed-on-mobile solution, which delivers calls over the mobile network without an app.

The softphone is just one part of your phone system, which you freely combine with a desk phone, a mobile or a SaaS application. Just like with the team dashboard, you decide yourself which device calls are offered on: the softphone, your desk phone or your existing mobile, and you adjust that setup at any time from the dashboard.

Request your number and we’ll get to work for you.

What it is on screen

A phone that happens to live in a window

The app registers with our platform using the credentials from your dashboard, then behaves like a handset: it rings, it shows who is calling, you answer, transfer or hang up. Step through the three states most people actually use.

The call arrives on the desktop

The number was dialled, the queue offered it to this person, and the app rang on a machine that was already awake. The caller’s number is shown, along with which of your business numbers they dialled — useful when you run more than one.

Answering here is a click or a headset button. There is no unlocking, no hunting for a handset and no waiting for an app to wake up, which is the difference between a softphone on a computer and the same app on a phone.

Talking, with both hands on the keyboard

Sarah answered with the headset button. The caller’s number and the number they dialled stay on screen for the length of the call, next to whatever she is typing into — the order system, a ticket, the CRM. Mute and hold are a click each, and the timer runs in the window rather than on a handset display across the desk.

Because the app is on the same machine as the work, there is nothing to reach for. That is the whole reason a headset and a softphone beat a handset for anyone who takes calls back to back.

Passing the call to a colleague

The caller needs accounts, not reception. Sarah picks Hannah from the app’s contacts and the call moves to Hannah’s desk phone in Manchester. The caller hears a moment of hold and then Hannah; nobody reads a number out loud and nobody dials again.

Any endpoint on the number can take a transfer — a desk phone, another softphone, a mobile over the mobile network. The caller never learns which, and Sarah’s line is free the moment it completes.

Outbound

Your business number, not your own

Calls you place from the app present the CallFactory number rather than anything personal. It is the main practical reason people who spend the day on the phone keep a softphone open even when a desk handset is sitting next to them.

The same is not true of a plain forward to a mobile — see fixed on mobile.

Hands

A headset is most of the point

With a USB or Bluetooth headset your hands stay on the keyboard, which is what makes a softphone genuinely better than a handset for anyone taking notes, filling in a system or checking an order mid-call.

Any mainstream USB or Bluetooth headset works — there is no certified list.

Network

Wired beats Wi-Fi for voice

The app carries the call over the internet, so call quality follows the connection. On a desk where reliability matters, a cable is worth more than any setting in the app. Wi-Fi works; it is simply the first thing to rule out when audio gets ragged.

Worth saying to whoever sets up the desks, before the first complaint.

Where it belongs, and where it does not

Excellent on a desktop. We would rather you did not rely on it on a phone.

This is the part most providers leave out of the brochure, and it is the reason we sell two different things for two different situations. A softphone on a computer is a proper business phone. The same app on a mobile inherits every weakness of being an app.

Recommended

On a desktop or laptop

The window stays open, the registration holds, and the call rings on a machine that is already awake and plugged in. For anyone sitting at a computer all day, this fully replaces a desk handset.

  • Rings reliably, because nothing is putting the app to sleep to save battery.
  • Headset, hands free, and the caller’s details on the same screen as your notes.
  • Outbound calls present the business number.
  • Cheaper than buying a handset for every desk, with the same calling experience.

Use it here. This is what it is for.

Not recommended

On a mobile phone

It works, and plenty of providers stop the sentence there. What they do not say is that a mobile operating system will close, suspend or throttle a background app whenever it feels the need — and a suspended app cannot ring.

  • The call fails silently. You do not find out; the customer does.
  • Battery optimisation is on by default, and it is not on your side.
  • Needs a connection good enough for voice at that exact moment.

Ask yourself how important it is to receive every call. If the answer is very, use fixed on mobile instead — it comes over the mobile network, with no app in the path. Our article on why business calls go missing on a VoIP app explains why.

Most teams run both: the softphone at the desk, mobile-network forwarding when they leave it. Both are set per person from the same dashboard.

Why we do not have our own app

A home-brew softphone is a liability wearing a logo

Every provider is tempted to build one, because an app with your name on it looks like a product. The trouble is that a softphone is not a screen — it is codecs, NAT traversal, network recovery, echo cancellation and two decades of edge cases on five platforms. A telecoms company doing that on the side produces something that mostly works, right up until the moment it matters.

Compared on
Typical provider An in-house app
Through CallFactory Linphone
who builds it
A telecoms company, without softphone expertise
Belledonne Communications, building softphones since 2001
platforms
Usually iOS and Android only
Windows, macOS, Linux, iOS and Android
development
Ad hoc, when something breaks or a customer insists
Continuous, by a dedicated team whose only product this is
source code
Closed. You install it and hope
Fully open source — inspect it, audit it, contribute to it
who else uses it
That provider’s own customers
Orange, BT, Swisscom and Taiwan Mobile, among others
if the provider leaves
The app goes with them
The project continues; it does not belong to us

For anyone with a security review to pass, the open-source part is not a talking point — it is the whole answer.

Larger organisations and public bodies are increasingly asked what exactly is being installed on staff equipment and what it talks to. With a closed provider app the honest answer is a shrug and a PDF. With Linphone you can read the source, have your own people audit it, and point at a published contributor list rather than at our word. That is a question we would rather be able to answer than deflect.

open source · published client list · independent of us · the same app on all five platforms

What it costs to run

You pay for the licence, not for everyone who ever holds it

Licences and VoIP accounts are issued and managed from your CallFactory dashboard — no second portal, no provisioning ticket. And because a licence is tied to a serial number rather than to a person, it goes back in the pool when somebody leaves.

  • Reassign instead of re-buy

    A colleague leaves in March and their replacement starts in May. The licence sat idle for six weeks and then went to the new person. Nothing was cancelled, nothing was bought, and nobody had to remember to do either.

  • Per-user pricing quietly ratchets

    On platforms that charge per named user, turnover is a cost. Every arrival adds a seat, and the departures only come off the bill if someone notices and removes them. Plenty of organisations are paying for people who left two years ago.

  • Set up in minutes, from the same screen

    Add a VoIP account, assign a licence, hand the credentials to the person. No separate vendor account, no downloads chased through support, and no waiting on us to provision anything.

  • Only for the people who need one

    Not everyone on the team needs a softphone. Someone in the field is better served by mobile-network forwarding, which does not need a licence at all — so you buy them for the desks, not for the headcount.

Softphone licences 2 of 3 in use
LIC-8841-A Assigned
Sarah Whitfield · desktop · since Jan
LIC-8841-B Assigned
Daniel Osei · desktop · since Mar
LIC-8841-C Available
released 6 May · ready to reassign

Licence identifiers are illustrative. Releasing a licence takes effect immediately and it can be assigned to a new VoIP account the same day, at no extra cost.

Getting it running

Four fields, the same four as a desk phone

A softphone registers exactly the way a SIP handset does, which means there is nothing special to learn and nothing for us to configure at our end. If your IT partner has set up a desk phone before, they have already done this.

  1. 01

    Add a VoIP account

    In the dashboard, create an account for the person and assign them a licence. This generates the credentials shown on the right.

  2. 02

    Install Linphone

    Downloaded from the dashboard for Windows, macOS or Linux. Nothing is compiled, patched or wrapped by us — it is the upstream application.

  3. 03

    Enter the four fields

    Username, password, server, port and transport. The app registers with our platform and the entry in your team list goes green.

  4. 04

    Decide what rings it

    On its own, alongside a desk phone, or in a queue behind reception. Set from the dashboard and changeable at any time, per person.

VoIP account · Sarah Whitfield Registered
SIP username
1042-swhitfield
Password
••••••••••••
Server
sip.callfactory.co.uk
Port · transport
5060 · TLS

The same credentials a desk handset takes. A person can register a softphone and a desk phone on separate accounts and have both ring, or use one account on the machine they are actually at.

The rest of the system

One endpoint among several, on the same number

A softphone is rarely the whole setup. The usual arrangement is a softphone and a desk phone ringing together in the office, with mobile-network forwarding taking over the moment somebody leaves it.

Fixed on mobile

The business number forwarded to a mobile over the mobile network, with no app in the path. What we recommend instead of a softphone on a phone.

See how it works

Desk phone

Any SIP handset from any supplier, taking the same four credentials as the softphone. Often both, ringing at once.

See how it works

Team dashboard

Who is available, who is mid-call and who is next. Where a softphone user marks themselves away without touching the routing.

See how it works

AI voicebot

Behind the queue for evenings and overflow, or in front of it to work out which team the caller actually needs.

See how it works

Web interface

Where VoIP accounts, licences, routing and hours are configured. The admin layer above every endpoint on this page.

See how it works

Call insights

Who called, when, how long and where it was routed — including the calls that rang a softphone and went unanswered.

See how it works
Every feature of the phone system — queues, menus, recording, voicemail-to-email, call insights — comes with the number itself, whichever endpoints you end up using. See all features →
Questions

Softphones — frequently asked questions

Yes. Our platform speaks standard SIP, so any compliant softphone can register with the credentials from your dashboard. We supply, licence and support Linphone because it is the one we would choose ourselves — but nothing stops you using another, and your existing one will very likely work.

It runs, but we do not recommend relying on it. A mobile operating system can suspend or close a background app, and a suspended app cannot ring — the failure is silent and lands on the caller. For calls that must arrive, use fixed on mobile, which is delivered over the mobile network with no app involved.

Strongly recommended on a desktop. It is better audio and, more to the point, it keeps your hands free to type during the call — which is most of the reason to prefer a softphone over a handset. Any mainstream USB or Bluetooth headset works.

Yes — the call is carried over the internet. Quality follows the connection, so a wired network connection is worth more than any setting in the app. It is the first thing to check if audio is ragged.

Your CallFactory business number. Outbound calls from the softphone present the business identity rather than anything personal, which is one of the practical advantages over a plain forward to a mobile.

Yes, and it is the usual office setup. Both can ring at once, or in an order you set, and the pattern can change by time of day. You configure it from the dashboard, per person.

You pay for the licence, which is tied to a serial number rather than a named person. When a colleague leaves, release it in the dashboard and assign it to whoever replaces them at no extra cost. That is deliberately different from per-user pricing, where turnover quietly increases the bill.

Yes, with a public repository and a published contributor list. For organisations that have to state exactly what is installed on staff equipment, the source can be read and audited by your own people rather than taken on trust from us.

We do, for anything touching your numbers, accounts, licences or routing. The application itself is maintained upstream by Belledonne Communications, which is precisely the point — it is looked after by people who do nothing else.

Start with the number. Put it on whatever each person actually sits in front of.

A softphone at the desk, a handset on reception, mobile-network forwarding in the van — one number, one dashboard, and no decision here that cannot be changed next week.

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