VoIP Connectivity for Small Businesses: Getting Started

What is VoIP and why does it matter for small businesses?

VoIP — Voice over Internet Protocol — is phone calling delivered over your internet connection rather than a copper line. Your voice becomes data, travels over the network, and is rebuilt at the far end in real time. On a decent connection the audio is as good as, or better than, a traditional call.

Two things make this urgent for small businesses. First, business VoIP is usually cheaper than legacy telephony, with lower line rental and call costs than PSTN. Second, the UK's copper phone network is being switched off on 31 January 2027, after which any business still on PSTN or ISDN must have migrated. Openreach's industry-wide move from analogue to digital lines is overseen by Ofcom, who publish guidance for businesses on the transition (Ofcom).

Around 2.4 million UK businesses still operate on PSTN or ISDN lines, the majority being SMEs, with roughly 33% of large corporations still relying on analogue for some communications *(Aircall)*. Getting ahead of the deadline now beats scrambling in 2027 — and the planning ties directly into your wider PSTN switch-off project.

What do you need to run VoIP in a small office?

You need three things to run VoIP well: a stable internet connection with low latency, a cloud phone platform to route and manage calls, and — optionally — VoIP handsets. None of these is exotic, but each has to be sized correctly or call quality suffers.

A reliable internet connection

VoIP needs working bandwidth and, more importantly, low latency. Each concurrent call uses roughly 85–100Kbps (typical for a standard voice codec), so a five-person office running three simultaneous calls needs about 300Kbps — trivial for any modern business broadband. Latency matters more than raw speed: calls turn choppy once one-way latency passes the standard 150ms quality threshold. A standard FTTC or FTTP line is more than enough for most small offices.

A VoIP provider or hosted phone system

You need a cloud platform to handle calls. Options run from simple softphone apps that turn a laptop or mobile into a phone, up to a full hosted phone system with call queuing, auto-attendant, call recording, and extension management. UK platforms in common use include RingCentral, 3CX, Gamma Horizon, and 8x8.

Pricing for a hosted PBX with standard features typically starts from £5.95 per user per month, which usually compares well against the per-line cost of ISDN or legacy hosted PABX systems.

VoIP-compatible handsets (optional)

You do not necessarily need desk phones. Many small businesses run VoIP entirely through desktop and mobile apps. If you do want physical handsets, models from Yealink, Cisco, and Poly (formerly Polycom) work with every major hosted PBX. The point is flexibility: staff can take their extension anywhere there is internet.

Should small businesses use Microsoft Teams for calling?

If you already run Microsoft 365, Microsoft Teams Calling deserves a serious look. With the Teams Phone add-on, Teams becomes a complete phone system — you make and receive external calls through the Teams app on any device, using your existing business numbers (Microsoft Learn).

Teams Calling needs either a Microsoft Calling Plan, where calls are billed by Microsoft from £5.95 per user per month, or Direct Routing, where calls run through a third-party SIP trunk provider. For modest call volumes the Calling Plan is the simplest path; for heavier users, Direct Routing usually reduces per-minute costs. One provider handling both your Microsoft tenancy and your telephony keeps the setup accountable to a single, Microsoft-certified team.

What about call quality, number porting and outages?

The three concerns small businesses raise most are call quality, keeping their numbers, and what happens in an outage. All three are solved problems when VoIP is configured by someone who does it for a living — and each comes down to the connection and router as much as the phone platform.

• Call quality. VoIP is excellent on a stable connection. Most quality problems come from network congestion, fixed by configuring QoS (Quality of Service) on the router to prioritise voice. AMVIA sets this as standard when deploying VoIP for clients.
• Number portability. You keep your existing geographic (01/02) and non-geographic (03/08) numbers. Porting typically takes 5–15 working days and is managed by your new provider, with calls forwarded throughout so nothing is missed.
• Outage cover. Because VoIP needs internet, mission-critical sites should add a 4G/5G failover on the router, with automatic call forwarding to mobile as a backup. Continuity is maintained without anyone touching a thing.

Because calls now ride your data network, VoIP security is part of the same conversation — call traffic, the platform, and the devices that connect to it all need protecting. Independent guidance on securing voice and collaboration services is published by the NCSC.

How do you migrate to VoIP without disruption?

A clean migration follows a short, predictable sequence and takes most small businesses two to four weeks from decision to live system. The key is doing the connectivity and the phone platform together, so the two are tuned to each other rather than bolted on afterwards.

• Confirm broadband speed and latency are adequate (run a speed test at peak hours).
• Choose a hosted phone platform, or use Teams Calling if you already run Microsoft 365.
• Decide on physical handsets versus software-only.
• Port your existing numbers to the new platform.
• Configure QoS on the router to prioritise voice traffic.
• Brief your team on the new system.

The reliability case for moving is hardening, too: PSTN resilience incidents climbed around 45% in 2024, with over 2,600 major PSTN resilience incidents logged across 2024/25 as the copper network is wound down *(UK 2024/25 data)* — and Europe's SIP trunking market is forecast to grow at a CAGR of 9.8% as PSTN retirements bite *(Zion Market Research, 2025)*. Legacy lines are getting less dependable, not more. AMVIA delivers the VoIP setup alongside your connectivity, so both are configured correctly together from day one — one provider, security-first, Microsoft-certified.