Glossary · Phone system (PBX)
Softphone
In one sentence
A softphone is a phone application that runs on a computer or smartphone. It replaces the desk phone and connects to the company phone system over VoIP, using the business number.
Also known as : softphones · softphone app · software phone
What is a softphone?
A softphone is a telephone that exists only as software. Installed on a Windows PC, a Mac, an iPhone or an Android handset, it does everything a desk phone does: dialling, hold, transfer, voicemail and showing whether colleagues are free. You talk through a headset or the device’s own microphone and speaker.
To the phone system, a softphone is simply another extension. It has its own internal number, its own forwarding rules, and it can call out showing the company’s number. That is how someone working from home or on the road stays reachable on their business line without handing out a personal mobile number.
How it works
- The app registers with the phone system or carrier, usually over SIP, using credentials that belong to that user.
- When a call comes in, the phone system offers it to the softphone, which rings on screen, or through a push notification on a mobile.
- Your voice is digitised by a codec, split into packets and carried as VoIP over whatever connection is available: office broadband, home Wi-Fi or mobile data.
- Features such as transfer, conferencing and recording run on the phone system; the softphone is the remote control.
Call quality depends mostly on the local network. Congested home Wi-Fi or a badly configured VPN adds delay and jitter, which you hear as choppy or robotic audio. A wired connection and a decent USB headset solve most complaints.
Example
A Dublin-based recruitment firm with twelve consultants moved off its ageing on-site system to a cloud PBX. Desk phones were not replaced: consultants run the softphone on their laptops with USB headsets and the mobile app when visiting clients. Candidates still call the same 01 number, a ring group alerts everyone logged in, and whoever answers can pass the call to the right consultant in two clicks, even if that person is working from home in Galway that day.
Softphones at Universal Telecom
Every user on our virtual PBX gets a desktop softphone and a mobile app, plus a webphone for anyone who would rather not install anything. If you keep your own PBX, most standard SIP softphones can register to it and reach the outside world through our SIP trunk. Not sure what your team needs? Get in touch.
Frequently asked questions
Do softphones work on mobile data?
Yes. A softphone app works over 4G or 5G as well as Wi-Fi. A stable connection matters more than raw speed: a voice call needs well under 100 kbps each way, but it suffers if packets arrive late or out of order.
Is a softphone as secure as a desk phone?
It can be, provided calls are encrypted (SIP over TLS and SRTP), each user has a strong unique password and the device itself is kept updated and locked. Most hosted platforms enforce encryption by default.
Related terms
- Webphone
A webphone is a business phone that runs in a browser tab with nothing to install. It uses WebRTC to make and receive calls through the company phone system on the business number.
- VoIP
VoIP (voice over internet protocol) carries phone calls as packets of data over an IP network, such as the internet or an office LAN, instead of over the copper lines of the traditional phone network.
- SIP
SIP (Session Initiation Protocol) is the standard signalling protocol that sets up, changes and ends VoIP calls. It handles ringing, answering and hanging up; the voice itself travels separately.
- Cloud PBX
A cloud PBX is a business phone system run by a provider in its data centres. Extensions, IVR menus, queues and call routing are managed from a web portal, with no PBX hardware on site.
- Extension
An extension is a short internal number, usually three or four digits, given to a user or device on a business phone system. Colleagues dial it to reach each other, and the system uses it to route calls.
- Jitter
Jitter is the variation in the arrival time of voice packets. When it exceeds what the phone's jitter buffer can absorb, packets are discarded and the voice sounds choppy or robotic.
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