Switching Analogue Lines to VoIP: What to Expect

If your business still uses traditional analogue phone lines — the kind with a copper pair running from the wall socket to the local exchange — you will need to replace them before the PSTN switch-off in January 2027. Analogue lines, also called POTS (Plain Old Telephone Service), are being retired along with the rest of the copper network.

Switching from analogue to VoIP is straightforward when planned properly. This guide explains what to expect at each stage so there are no surprises.

What Are Analogue Phone Lines?

Analogue lines are the original telephone technology. Each line provides a single voice channel over a dedicated copper pair. Characteristics include:

• One call per line — if you need three simultaneous calls, you need three lines.
• Basic features only — caller ID, call waiting, and 1471 are about as advanced as it gets.
• Reliable during power cuts (the exchange provides power), but no modern features like voicemail-to-email, call recording, or integration with business software.
• Used not just for voice but also for fax machines, alarm systems, EPOS terminals, and lift emergency phones.

Why Analogue Lines Are Being Switched Off

Openreach is retiring the entire copper-based telephone network. This affects:

• Every analogue phone line in the UK
• All ISDN circuits (ISDN2 and ISDN30)
• ADSL broadband services that run over the same copper

The replacement is an all-IP network. Voice calls will be carried over broadband using VoIP instead of dedicated copper circuits.

What Replaces Analogue Lines?

For businesses, the most common replacements are:

• Hosted VoIP: A cloud phone system that provides desk phones, softphones (apps on your PC or mobile), and all the features a modern business needs — auto attendants, call queues, voicemail-to-email, call recording, and more.
• SIP trunks: If you have an existing PBX that supports SIP, SIP trunks replace your analogue lines and connect the PBX to the phone network over broadband.
• Microsoft Teams telephony: If you use Microsoft 365, Teams with Direct Routing or Operator Connect can act as your phone system.

The right choice depends on your current setup, budget, and how many features you need.

What to Expect: The Migration Process

Here is what a typical analogue-to-VoIP migration looks like for a small or medium business:

Week 1–2: Discovery and audit

• Your provider surveys your current analogue lines — how many, what numbers, and what they connect to.
• Non-voice devices on analogue lines are identified: fax, alarms, EPOS, and lift phones each need a specific migration path.
• Your broadband is tested for VoIP readiness (speed, latency, jitter).

Week 2–3: Solution design and quoting

• Based on the audit, your provider recommends a VoIP solution and provides a detailed quote.
• You agree on which numbers to port, which features to enable, and the hardware you need (if any).
• If your broadband needs upgrading, the upgrade is ordered now to run in parallel.

Week 3–5: Number porting and provisioning

• Your provider submits number porting requests to move your existing numbers from the analogue carrier.
• Porting takes 10–20 business days. During this time, your phones continue to work normally.
• The VoIP system is configured — extensions, call routing, voicemail, greetings, and user accounts.
• Handsets and hardware are shipped and pre-configured.

Week 5–6: Installation and go-live

• Handsets are installed and connected to your network.
• On the porting completion date, calls automatically route to the new VoIP system.
• Your provider runs final tests — inbound, outbound, transfers, and voicemail.
• Staff receive a brief walkthrough of the new phones and features.

Post go-live: Support and optimisation

• Your provider monitors call quality for the first few weeks.
• Any teething issues (routing errors, audio quality, configuration tweaks) are resolved.
• Old analogue lines are cancelled to stop billing.

What About Devices on Analogue Lines?

Analogue lines often carry more than voice. Here is how to handle common non-voice devices:

Fax machines: Replace with a fax-to-email service. Incoming faxes arrive as PDF attachments in your inbox. Outgoing faxes are sent from a web interface. Physical fax machines can connect via an ATA (analogue telephone adapter) if you must keep them.

Burglar and fire alarms: Contact your alarm company about switching to an IP or GSM (mobile network) communicator. Most modern alarm panels support both options.

EPOS/card payment terminals: Most modern terminals already use broadband or 4G. If yours still uses a phone line, your payment provider will supply an updated terminal.

Lift emergency phones: A GSM gateway replaces the analogue line, connecting the lift phone to the monitoring centre via the mobile network.

Door entry systems: SIP-compatible door entry panels work over your network. Alternatively, GSM intercoms provide a simple replacement.

Will I Notice a Difference?

In terms of call quality, VoIP over a good broadband connection sounds as good as — or better than — an analogue line. HD voice codecs provide richer, clearer audio than the narrow bandwidth of analogue.

The biggest difference is features. You will gain voicemail-to-email, call recording, auto attendants, mobile apps, and much more. Most businesses wonder why they did not switch sooner.

The one thing to be aware of is power dependency. Analogue lines work during power cuts because the exchange provides power. VoIP requires your broadband router and phones to have power. A small UPS (uninterruptible power supply) solves this for critical lines.

For a detailed walkthrough of the migration experience, see our guide to managed VoIP migration. For a broader comparison of hosted VoIP platforms, read our review of hosted VoIP solutions in the UK.