Softphone
A softphone is an application that makes and receives phone calls over the internet using a computer, phone or tablet instead of a dedicated handset. Most use SIP.
Published 8 November 2026 · Updated 9 November 2026 · 1 min read · By SpaGreen Creative
Short answer
A softphone is software that acts as a telephone on a general-purpose device, registering with a SIP server and using the device's microphone and speaker to place and receive calls.
A softphone does the job of a desk phone in software. Installed on a computer, phone or tablet, it registers with a PBX or provider using SIP, shows a dial pad and call controls, and uses the device's own audio hardware or a headset for the conversation. Everything a hardware SIP phone does, from registration to codec negotiation to DTMF, happens inside the app.
The advantages are cost and flexibility. There is no hardware to buy or install, the same extension can follow a person between devices, and features such as call history, recording and contact lookup are easier to build in software. The disadvantages are dependence on the host device: audio quality depends on the microphone and headset, and on mobile platforms the operating system limits what an app can do in the background, which affects whether calls can be received when the app is not open.
Softphones range from free open source projects to paid commercial products, and from generic SIP clients that work with standards-based servers from many vendors to provider-locked apps that only connect to one service. SIPdia is a generic SIP softphone for macOS, iOS and iPadOS that works with standards-based PBX systems and providers.
Sources and further reading
- RFC 3261: SIP: Session Initiation Protocolwww.rfc-editor.org
This article is published by SpaGreen Creative, the maker of SIPdia. Product names mentioned belong to their owners. Where it describes other software, treat the steps as general guidance and check the official documentation linked above.
