Assess whether your current network infrastructure can support a VoIP phone system, and get upgrade recommendations if needed.
| Codec | Per Call (Kbps) | 5 Calls | 10 Calls | 25 Calls | 50 Calls |
|---|---|---|---|---|---|
| G.711 (HD Voice) | 87 Kbps | 0.44 Mbps | 0.87 Mbps | 2.18 Mbps | 4.35 Mbps |
| G.729 (Compressed) | 32 Kbps | 0.16 Mbps | 0.32 Mbps | 0.80 Mbps | 1.60 Mbps |
| G.722 (Wideband) | 80 Kbps | 0.40 Mbps | 0.80 Mbps | 2.00 Mbps | 4.00 Mbps |
| Opus (Adaptive) | 40–80 Kbps | 0.20–0.40 | 0.40–0.80 | 1.00–2.00 | 2.00–4.00 |
Bandwidth figures include protocol overhead (IP/UDP/RTP headers). Actual usage varies by codec settings, silence suppression, and network conditions. We recommend reserving 30% additional headroom for data traffic. Talk to our VoIP team
Try our other free IT calculators and planning tools.
VoIP typically needs at least 100kbps of stable bandwidth per concurrent call, plus low latency (under 150ms) and minimal packet loss for clear audio. Older routers, congested WiFi, or a connection already saturated by cloud backups are the most common causes of choppy VoIP calls in UK SMEs - this checker scores your setup against all of these factors.
Quality of Service (QoS) is a router or firewall setting that prioritises voice traffic over less time-sensitive data like file downloads, preventing calls cutting out when the network is busy. Most consumer-grade routers lack proper QoS controls, which is why many UK SMEs need a business-grade firewall upgrade before rolling out VoIP.
Dropped or choppy VoIP calls are usually caused by insufficient bandwidth, high network jitter, or lack of QoS prioritisation on the router, often made worse by WiFi interference if handsets aren't on a wired connection. Ageing network switches and routers over 5 years old are also a common culprit worth checking first.
It depends on your current setup - many offices can run VoIP successfully on existing infrastructure if it supports QoS and has sufficient bandwidth headroom, but businesses with older unmanaged switches or consumer routers typically need a £200-£1,000 hardware upgrade first to guarantee call quality.
Powered by industry-leading technologies including SolarWinds, Cloudflare, BitDefender, AWS, Microsoft Azure, and Cisco Meraki to deliver secure, scalable, and reliable IT solutions.
6 Oct, 2026
M365 email archiving is the thing most UK businesses believe they have and very few have configured. The belief usually comes from a reasonable source...
3 Oct, 2026
VoIP security is usually discussed as a technical problem, and the technical controls are well understood encryption for signalling and media, session border...
1 Oct, 2026
A business ISP comparison conducted on headline speed and monthly price will mislead you on both counts. The speed is frequently an up to figure describing a...