Home VoIP & Digital Voice Explained

The Telephone Is Invented

Alexander Graham Bell patented the telephone in 1876 and the first telephone exchanges opened in the UK in 1879. By the early 1900s telephone networks were expanding rapidly across British towns and cities. The copper wire network that would eventually become the PSTN began to take shape — a network that would serve UK homes and businesses for over a century.

Digital Telephony and the PSTN

The telephone network evolved from analogue to digital switching through the 1970s and 1980s, improving call quality and capacity significantly. BT was privatised in 1984 and the modern PSTN became the backbone of UK voice communications, carrying billions of calls annually over the copper wire infrastructure that most UK homes are still connected to today.

VoIP Is Born

The first VoIP application — VocalTec Internet Phone — was released in 1995. As broadband internet expanded through the early 2000s, VoIP became increasingly practical. Skype launched in 2003 and introduced millions of people to the concept of making telephone calls over the internet. Businesses began replacing expensive ISDN lines with SIP trunks and hosted VoIP systems.

VoIP Goes Mainstream

WhatsApp, FaceTime, and later Teams and Zoom brought VoIP into everyday life for hundreds of millions of people — most of whom did not realise they were using VoIP at all. Meanwhile UK businesses accelerated their migration from traditional ISDN lines to hosted VoIP systems, driven by cost savings, flexibility, and the arrival of cloud-based PBX systems requiring no on-site hardware.

The PSTN Switch-Off — VoIP for Every UK Home

BT Openreach is retiring the UK's copper telephone network and replacing it with VoIP-based Digital Voice services. Every UK home and business with a traditional landline will transition to VoIP. The switch-off is rolling out exchange by exchange across the UK with full completion targeted by 2027. See our dedicated UK Landline Switch-Off page for the complete guide to what this means for your home.

☎️ Option 1 — Your Provider's Digital Voice Service

Most UK broadband providers — including BT, Sky, Virgin Media, TalkTalk, and Vodafone — now offer a Digital Voice service that migrates your existing landline number to VoIP automatically. Your provider will contact you ahead of the switch in your area and handle the migration.

🔌 Option 2 — ATA Adapter With Your Existing Handset

An Analogue Telephone Adapter (ATA) is a small device that plugs into your broadband router and provides a standard telephone socket — allowing you to plug in your existing analogue handset and use it for VoIP calls. This is the simplest and cheapest way to keep using a phone you already own.

📞 Option 3 — Dedicated VoIP Handset

A dedicated VoIP phone connects directly to your router via ethernet or Wi-Fi and handles VoIP calls natively — no ATA adapter required. Many modern cordless DECT phone systems include VoIP functionality built in, giving you a traditional cordless phone experience over VoIP.

📱 Option 4 — Softphone App on Your Smartphone

A softphone is a VoIP application installed on your smartphone, tablet, or computer that lets you make and receive calls on your home number from any device — without needing a physical phone at all. Particularly useful for households that mostly use mobile phones and simply want to retain a landline number.

Check Your Broadband Is Suitable

VoIP needs a stable broadband connection with at least 1Mbps upload speed — which virtually all UK broadband connections provide. What matters more than speed is stability. If your broadband regularly drops out, resolve this first before setting up VoIP. Use our free Broadband Speed Checker to confirm your connection quality before you start.

Choose Your VoIP Provider and Get Your Credentials

If your broadband provider is migrating you to Digital Voice, they will supply your VoIP credentials as part of the migration. If you are choosing a separate VoIP provider, sign up for an account and they will supply a username, password, and SIP server address — these are what you enter into your phone or adapter to register the service.

Set Up Your Equipment

Depending on your chosen option — router phone port, ATA adapter, VoIP handset, or softphone app — follow the setup instructions supplied by your provider or device manufacturer. Most modern VoIP phones and ATAs have a simple web-based admin page where you enter your SIP credentials. Softphone apps guide you through setup with a step-by-step wizard.

Register Your Address for 999 Emergency Calls

Unlike traditional landlines, VoIP calls do not automatically transmit your address to the emergency services. You must register your address with your VoIP provider to ensure that if you call 999 and cannot speak, your location can be identified. Your provider will have a process for this — do not skip this step.

Consider a UPS for Power Cut Protection

Traditional landlines work during power cuts because they draw power from the telephone network. VoIP phones require your router to be powered and online. If your home phone is important during power outages, consider a small UPS — Uninterruptible Power Supply — to keep your router running for 30–60 minutes during a power cut. See our Ethernet & Switches guide for UPS recommendations.

Test Your Setup Thoroughly

Make several test calls — incoming and outgoing — to different types of numbers including mobiles, other landlines, and 0800 numbers. Check call quality at different times of day. Confirm voicemail works if your provider includes it. If you are running VoIP alongside a copper line during migration, test thoroughly before your existing line is disconnected.

Poor Call Quality — Choppy, Distorted, or Echo

Audio issues on VoIP calls are almost always caused by insufficient bandwidth, network congestion, or a poor Wi-Fi connection between the phone and router.

Cannot Make or Receive Calls at All

A complete inability to make or receive calls usually indicates a registration problem — your VoIP device is not successfully connected to your provider's SIP server.

Phone Does Not Work During a Power Cut

Unlike traditional copper landlines, VoIP phones require mains power and a working broadband connection. A power cut will stop VoIP service unless you have battery backup in place.

Concerns About 999 Emergency Calls

VoIP services in the UK are required to support 999 emergency calls — but unlike traditional landlines, your location is not automatically transmitted unless you have registered it with your provider.