Cut Your Phone Bills by Up to 70% — Without Losing a Single Feature

This is the hub for everything VoIP. Below, work through how it works, what it costs, how it compares to legacy ISDN, and which path fits your business — then drill into the detailed pages on hosted phone systems, Microsoft Teams Direct Routing and the PSTN switch-off migration.

What is business VoIP and how does it work?

Business VoIP (Voice over Internet Protocol) carries phone calls as data over your broadband or leased line rather than over the traditional copper telephone network. A cloud platform replaces the physical PBX, so calls, voicemail and routing all run in software you manage through a web portal.

Because the exchange lives in a data centre, features that used to need extra hardware come as standard:

• Auto-attendant and IVR call menus
• Call recording for compliance
• Hunt groups, call queuing and voicemail-to-email
• Desk phone, softphone and mobile-app calling on one number
• Provisioning of new users in minutes, not site visits

For the underlying technology and call-quality guidance, Microsoft documents its cloud calling stack in detail on Microsoft Learn.

Why do UK SMEs need to move to VoIP now?

The analogue phone network is being switched off. The old PSTN and ISDN lines that carried UK business calls for decades are being retired as Openreach migrates every line to all-IP, with stop-sell orders on new PSTN and ISDN lines already in force. Any business still on a legacy line needs a migration plan.

The switch-off completion deadline is 31 January 2027, confirmed by the UK telecoms regulator Ofcom. Many businesses have already been shifted onto basic "Digital Voice" products that are not equivalent to a full hosted VoIP system — they replace the line but not the phone system. Moving deliberately, rather than being defaulted onto a cut-down product, protects your numbers, your features and your call quality.

Treat the migration as a security project as well as a telephony one — voice traffic carries sensitive data, which is why we cover hardening on our VoIP security page in line with NCSC guidance.

VoIP vs traditional ISDN landlines: how do they compare?

VoIP removes per-channel line rental and bundles enterprise features that ISDN charged extra for. The headline difference is cost and flexibility: lines provision in minutes through a portal instead of waiting on physical installation.

AMVIA customers typically cut phone bills by up to 70% versus traditional ISDN line rental — a typical 2026 saving — while gaining features ISDN never offered.

Is Microsoft Teams the same as business VoIP?

Not on its own. Microsoft Teams includes chat, video and file sharing but does not include PSTN calling by default — it cannot dial or receive normal phone numbers until you add a calling capability. There are two routes, and the right one depends on call volume and number flexibility.

Teams Phone is a serious, widely adopted enterprise phone platform — not a video add-on. AMVIA adds dialling through Direct Routing or a dedicated SIP trunk, connecting your Microsoft 365 environment straight to the telephone network.

What internet speed do you need for VoIP?

Each concurrent VoIP call needs roughly 100 kbps of symmetrical bandwidth — a standard 2026 codec planning figure — so ten simultaneous callers need around 1 Mbps reserved for voice. That is modest, but it must be consistent — jitter and packet loss, not raw speed, are what break calls.

For 20+ concurrent calls or guaranteed quality, a leased line gives uncontended, symmetric bandwidth and predictable latency. Businesses running high call volumes alongside cloud apps should size connectivity deliberately, and our multi-site VoIP page covers routing across locations.

What does business VoIP cost?

Every business specs differently — call recording, Teams routing, compliance storage, handsets — so we publish honest per-user ranges instead of a teaser rate that doubles at quote stage. Essentials starts from £5.95/user/month (unlimited UK calls, apps, auto-attendant); Business typically runs £10–£14/user, adding call recording, Microsoft Teams and CRM integration and multi-site support; Complete typically runs £15–£20/user with compliant call storage, full Teams Direct Routing and advanced analytics. The UK market norm for hosted VoIP is £12–£20/user, so even the mid tier undercuts most rate cards.

What moves you within a range, stated plainly: call-recording retention and compliance level, Teams Direct Routing versus app-only calling, number of sites, handset choice (rental or purchase, typically £50–£150 per IP handset), and contract term. Number porting is typically included. See the full breakdown in our VoIP cost guide.

A worked example: a typical 15-user business on the Business tier lands around £150–£210/month with UK calls included. The equivalent ISDN setup costs £25–£50 per channel in line rental before a single call charge — and those lines stop working on 31 January 2027 regardless. The maths and the deadline point the same way.

Which VoIP setup fits your business size?

The right architecture scales with headcount and compliance needs. Smaller teams want simplicity; larger SMEs need routing, recording and integration.

• Small businesses (5–25 staff): simple hosted VoIP with auto-attendant, voicemail-to-email and mobile-app calling. Teams Direct Routing is often most cost-effective if you already run Microsoft 365.
• Mid-market (25–100 staff): multi-site routing, call recording for compliance, CRM integration and call queuing. A dedicated cloud PBX with a management portal is the usual fit.
• Larger SMEs (100–500 staff): high call volumes need capacity planning, advanced IVR and call-centre features. AMVIA designs bespoke VoIP architectures and can deliver them as part of a wider UCaaS platform.