VoIP for 20 Users: Enterprise Features at SME Prices

Last updated: April 2026

Twenty users is where VoIP gets genuinely exciting. At this size, you unlock the best volume discounts most providers offer, you gain access to features that used to be reserved for large call centres, and your phone system becomes a serious business tool rather than just a way to make and receive calls. CRM integration, real-time wallboards, detailed reporting, call queuing with callbacks, supervisor monitoring. All of this is available at a fraction of what it would have cost five years ago.

We are Compare The Networks, an OFCOM-regulated telecoms comparison service based in Shrewsbury. We have been helping UK businesses with their phone systems since 2008, have a 4.3/5 Trustpilot rating from over 1,000 reviews, and we have set up VoIP for over 2,000 businesses. At twenty users, we start having conversations about call flow design, network architecture, and system management that go beyond the basics. This guide covers everything you need to plan a twenty-user VoIP deployment properly.

The PSTN switch-off completes in January 2027. If you are still on traditional phone lines, the deadline is real and approaching fast.

---

Costs at the 20-User Level

Twenty users is where VoIP pricing gets most competitive. You are past the threshold where every major provider offers their best volume discounts, and the per-user cost drops noticeably compared to smaller deployments.

Per User Pricing by Tier

Notice the per-user costs are lower across every tier compared to five or ten-user pricing. At twenty users, providers compete harder for your business because you represent meaningful recurring revenue for them.

Total Monthly Cost for 20 Users

For most twenty-user businesses, the Standard tier covers everything they need. If you have a dedicated sales team or customer service desk that would benefit from wallboards, CRM pops, and supervisor monitoring, the Premium tier for those specific users (mixed with Standard for everyone else) is the smartest approach.

Volume Discount Comparison Across Business Sizes

Over a 12-month contract, a twenty-user business saves roughly £480-720 compared to paying the five-user per-unit rate. That covers the cost of several desk phones.

Full Cost Comparison: VoIP vs Traditional for 20 Users

At twenty users, the cost difference between traditional and VoIP is staggering. A traditional PBX system for twenty people could easily cost £30,000 in the first year when you factor in hardware, installation, lines, and call charges. VoIP does the same job for under £5,000 per year, with better features and zero upfront capital expenditure.

Get your free 20-user VoIP quote. We compare multiple providers for you

---

Enterprise Features You Unlock at 20 Users

This is the section that matters most. At twenty users, you are not just getting phones that ring. You are getting a communications platform that actively helps your team perform better.

Call Centre Features

You do not need to be running a 100-seat call centre to benefit from call centre features. A twenty-person business with a sales team of five or a customer service desk of four is exactly the size where these tools start paying for themselves.

Call queuing: Instead of callers getting a busy tone or voicemail during busy periods, they enter a queue and hear their position. "You are caller number 3, please hold and we will be with you shortly." This alone can recover revenue that you are currently losing to abandoned calls.

Queue callbacks: When wait times are long, offer the caller a callback instead of making them hold. "Press 1 and we will call you back within 15 minutes." Your team calls them back when free, and the caller does not have to sit listening to hold music. This is a premium feature that makes a measurable difference to customer satisfaction.

Supervisor monitoring: A team leader can listen to live calls (silently), whisper coaching to the agent without the caller hearing, or barge into the call if needed. Essential for training new staff and maintaining quality standards.

Wallboards: Real-time displays showing queue stats: calls waiting, average wait time, calls handled today, longest wait. You can display this on a TV screen in the office or view it on a computer. It keeps the team aware of call volumes and helps managers spot problems before they become crises.

CRM Integration

At twenty users, connecting your phone system to your CRM (Salesforce, HubSpot, Zoho, Microsoft Dynamics, or others) stops being a luxury and starts being a productivity multiplier.

When a call comes in, the CRM automatically pops the caller's record on screen. Your team sees the caller's name, company, account history, and recent interactions before they even answer. No more "Can I take your name and look you up?" at the start of every call.

Outbound calls can be made with a single click from within the CRM. Call logs are automatically saved to the contact record. Notes and outcomes can be added during or after the call. This saves minutes per call, which across twenty users handling dozens of calls per day, adds up to hours of recovered productivity per week.

3CX integrates natively with most major CRMs. Setup takes about 30 minutes per CRM, and we handle the configuration as part of our deployment service.

Advanced Reporting and Analytics

At five or ten users, basic call stats are useful. At twenty, you need proper reporting. The kind that tells you:

• How many calls each team or individual handles per day, week, month
• Average call duration by team and individual
• Missed call rates and when they happen (time of day, day of week)
• Queue performance: average wait time, abandonment rate, service level
• Peak call periods so you can staff accordingly
• Call outcome tracking when integrated with CRM

These reports can be scheduled to land in your inbox weekly or viewed on demand through the admin portal. For a twenty-user business, this data often reveals surprises. You might discover that 30% of calls come in during the first hour of the day, or that one team member handles twice the volume of their colleagues. That kind of insight drives real operational improvements.

Multi-Level Auto-Attendant

At twenty users, your auto-attendant needs to handle more complexity. A typical setup might look like:

• Main greeting with business hours awareness (different message in and out of hours)
• Level 1: "Press 1 for Sales, 2 for Customer Service, 3 for Accounts, 4 for all other enquiries"
• Level 2 (Sales): "For new enquiries press 1, for existing customers press 2"
• Level 2 (Customer Service): "For order status press 1, for returns press 2, for technical support press 3"
• Each option routes to the appropriate call group with its own ring strategy and overflow rules

This call flow can be designed visually in 3CX's admin portal. You drag and drop call routing nodes on screen, set timeouts and overflows, and preview the entire call journey before going live. Changes can be made in minutes without calling your provider.

For background on features and how VoIP works, our hosted VoIP for business guide is a thorough reference.

---

Provider Comparison for 20 Users

At twenty users, provider selection is a strategic decision. You are committing to a platform that your entire team will rely on daily, and the annual spend is significant enough that getting it wrong is costly. Here is how the main options compare:

At twenty users, 3CX through Compare The Networks consistently comes out as the best value. The gap between 3CX and the alternatives is more pronounced at this size because 3CX includes call centre features (wallboards, queuing, supervisor tools) in its standard licensing, while most competitors charge extra for these or lock them behind premium tiers.

The flexibility of 3CX's SIP trunk model also matters more at twenty users. Because you can choose your own carrier for call minutes, you can optimise for your specific calling patterns. If you make a lot of mobile calls, we pair you with a carrier that has the best mobile rates. If you make international calls, we find the best rates for your destination countries. This kind of optimisation is not possible with providers that bundle everything into a single per-user price.

Compare providers and get a personalised 20-user quote, free and no obligation

---

Hardware Planning for 20 Users

At twenty users, hardware planning becomes a proper project rather than a quick decision. You are buying or leasing more phones, you probably have different requirements across departments, and getting the mix right saves money and improves the user experience.

Recommended Hardware Setup

Total hardware for a typical 20-user setup: £1,500-2,500 purchased, or £65-100+VAT/mo leased.

Headsets

At twenty users, headset quality matters. For desk-based staff using physical phones, a decent wired headset (£30-50) or wireless DECT headset (£80-150) makes a huge difference to comfort and productivity, especially for anyone on the phone for more than an hour a day.

For softphone users, a good USB or Bluetooth headset is essential. Budget £40-80 per user for a reliable headset from Jabra, Plantronics (Poly), or similar.

Purchasing vs Leasing at 20 Users

At twenty users, leasing becomes more attractive because the monthly cost is spread across enough users that it does not feel significant per person. Leasing also means phones are replaced when they reach end of life, which matters when you have twenty handsets to maintain.

---

Network Requirements at 20 Users

This is where network planning starts to matter. At five or ten users, you can plug VoIP phones into your existing network and it just works. At twenty, you should give your network a bit of attention to ensure consistent call quality.

Bandwidth

Twenty simultaneous VoIP calls use approximately 2Mbps up and 2Mbps down. On a standard 80/20 FTTC connection, that is still only 10% of your upload bandwidth. Plenty of headroom.

However, at twenty users, your general internet usage is also higher. Twenty people browsing, emailing, uploading files, and streaming video can put meaningful load on a broadband connection, especially the upload side.

Quality of Service (QoS)

At twenty users, we strongly recommend configuring QoS on your router. QoS marks voice traffic as high priority, ensuring it gets through even when the connection is busy with other traffic. Without QoS, a large file upload or cloud backup running in the background could degrade call quality for everyone.

Most business-grade routers support QoS out of the box. Configuration takes 10-15 minutes and the improvement in reliability during busy periods is significant.

Dedicated Voice VLAN

For twenty users, we recommend setting up a dedicated VLAN (Virtual Local Area Network) for voice traffic. This separates your VoIP phones onto their own logical network, isolated from your general data traffic. Benefits include:

• Security: Voice traffic is isolated from data traffic, reducing attack surface
• Performance: Voice packets are not competing with file downloads, cloud syncs, or web traffic
• Management: You can apply different network policies to voice and data
• Troubleshooting: If call quality drops, you can quickly identify whether it is a network issue or a VoIP issue

Setting up a voice VLAN requires a managed switch (a Netgear or TP-Link managed switch suitable for twenty users costs £100-200) and some basic configuration. We can advise on the setup, or your IT provider can handle it.

Broadband Recommendations

For most twenty-user businesses, a single FTTC connection with QoS configured is sufficient. If your business is data-heavy (large file transfers, video conferencing alongside voice calls, cloud-based workflows), consider dual lines or an FTTP connection if it is available at your premises.

---

Managed vs Self-Managed

At twenty users, you face a genuine choice about how much of the system management you want to handle yourself versus outsourcing to your VoIP provider.

Self-Managed

With a platform like 3CX, the admin portal is web-based and genuinely user-friendly. An office manager or IT-savvy team member can handle:

• Adding and removing users
• Changing call group memberships
• Updating auto-attendant messages and business hours
• Running call reports
• Managing voicemail settings
• Basic troubleshooting

This works well for businesses that like to have control and have someone willing to learn the system. The learning curve is modest. A couple of hours getting familiar with the portal, and most day-to-day tasks become routine.

Fully Managed

If you would rather not think about your phone system at all, we offer fully managed VoIP. You call or email us when you need a change, and we make it. New starter joining? We set up their extension, configure their phone, add them to the right call groups, and test everything. Someone leaving? We handle the offboarding. Need to restructure your call flow for a new department? We design and implement it.

For twenty-user businesses without an in-house IT function, fully managed makes a lot of sense. The cost is typically included in the monthly per-user fee or available as a small add-on.

Hybrid Management

Most of our twenty-user customers end up somewhere in the middle. They handle simple day-to-day changes themselves (changing a voicemail greeting, updating hold music, checking call stats) and come to us for anything structural (new departments, call flow redesigns, integrations, troubleshooting quality issues).

---

Training Considerations at 20 Users

Training twenty people requires a more structured approach than smaller deployments. You cannot rely on showing everyone one at a time.

Training Plan

Total training time: about half a day across all sessions. We handle all of this as part of our deployment service.

Ongoing Training

New starters need a quick introduction to the phone system. We provide written guides and short video tutorials that new employees can work through in 15 minutes. For the admin, we provide documentation covering all common tasks with step-by-step instructions.

---

Migration Planning

Moving twenty users from a traditional phone system to VoIP needs a bit of planning. Not because it is complex, but because you want to minimise disruption to your business.

Pre-Migration Checklist

• Audit your current phone numbers (which ones need porting, which can be retired)
• Map your current call flow (how calls are routed today, what needs to change)
• Decide on hardware (who gets desk phones, who gets softphones)
• Check broadband suitability (speed test, stability check)
• Plan your go-live date (avoid your busiest period)
• Brief your team (what is changing, when, and why)

Migration Approaches

Big bang: Everything switches over on one day. All twenty users go live at once. This is the most common approach and works well when your team is in one location and you have a few hours (usually a weekend or early morning) to test everything before the working day starts.

Phased rollout: Move departments or groups across in stages. Start with a less call-heavy team, iron out any issues, then move the rest. This takes longer overall but reduces risk. Works well for businesses that cannot afford any disruption.

Parallel running: Keep your old system active while running the new VoIP system alongside it for a week or two. This is the most cautious approach and costs a bit more (you are paying for both systems briefly), but it gives you a complete fallback if anything goes wrong.

For twenty-user deployments, we usually recommend the big bang approach with thorough testing before go-live. With proper preparation, the switchover is smooth, and you avoid the cost and complexity of running parallel systems. If you are experiencing any issues with your current VoIP setup, our VoIP problems and solutions guide covers common issues and fixes.

---

Scaling Beyond 20 Users

If your business is growing past twenty users, the good news is that modern VoIP scales seamlessly. On 3CX, adding users 21 through 50 is exactly the same process as adding users 1 through 20: provision a new licence, set up the extension, assign to call groups, and they are live.

The main considerations as you grow beyond twenty:

• Licensing tiers may change: Some providers have licence thresholds at 25, 50, or 100 users. Check what the next tier looks like before committing to a provider at 20 users.
• Network infrastructure: Above 30-40 concurrent users, you may want to review your switch infrastructure and consider a dedicated internet connection for voice.
• Support and management: Above 30 users, having a managed service agreement becomes increasingly valuable. The admin overhead of managing call groups, user permissions, and call flows for 30+ people is real.
• Call centre software: If your sales or support teams grow significantly, you might eventually want a dedicated contact centre platform on top of or alongside your VoIP system.

For smaller deployments, see our guides to VoIP for 5 users and VoIP for 10 users.

---

Frequently Asked Questions

What is the best VoIP system for 20 users in the UK?

Based on our experience deploying VoIP for thousands of UK businesses, 3CX consistently delivers the best combination of features, flexibility, and value at the twenty-user level. The call centre features (queuing, wallboards, supervisor monitoring) are included in the standard licence rather than being premium add-ons. The SIP trunk flexibility means you can optimise call costs for your specific usage. And the admin portal is powerful enough for twenty users without being overwhelmingly complex. Get a personalised comparison and we will show you exactly how the options stack up for your business.

Can I mix different phone types and software across 20 users?

Yes. This is exactly what most of our twenty-user customers do. Your receptionist might have a premium touchscreen phone, your sales team might have mid-range desk phones, and your field workers might use the mobile app exclusively. Everyone is on the same system, can transfer calls between each other, and shows up in the same directory and presence view. You can also mix licence tiers, putting power users on Premium and everyone else on Standard.

Do I need a dedicated IT person to manage VoIP for 20 users?

No. A motivated office manager or operations person can handle day-to-day VoIP administration with a couple of hours of training. The admin portal for platforms like 3CX is web-based and intuitive. Adding users, changing groups, and running reports are straightforward tasks. For anything more complex (call flow design, CRM integration, troubleshooting), we handle it as part of our support service. You do not need to hire an IT specialist for this.

How do wallboards work and are they worth it?

Wallboards are real-time dashboards that display call queue statistics: calls waiting, average wait time, calls answered today, longest wait, service level percentage. You can display them on a TV screen in the office or view them on any computer. They are worth it if you have a sales or customer service team of four or more people. The visual feedback keeps teams aware of call volumes and creates healthy accountability. On 3CX, wallboards are included in the standard licence.

What happens during a power cut?

If your office loses power, your desk phones and router will go down. However, a properly configured VoIP system handles this gracefully. Calls automatically divert to mobile numbers or another location. The mobile app continues working over 4G/5G. Voicemail captures any messages. For businesses that need continuous availability, an uninterruptible power supply (UPS) for your router and network switch (£100-200) keeps your internet and VoIP running for 30-60 minutes during a power cut, which covers most brief outages.

Is 20 users too small for CRM integration?

Not at all. CRM integration delivers the biggest per-user productivity gains in businesses between 10 and 50 users. At this size, everyone knows their customers personally, and having the caller's record pop up instantly reinforces that personal touch. The time saved per call (no looking up records, no asking for details they have already given) multiplied across twenty users and dozens of daily calls adds up to hours of recovered productivity per week.

---

Next Steps

If you are running a twenty-user business, or planning to grow to that size, VoIP is not just a phone system upgrade. It is a business operations upgrade. The combination of cost savings, enterprise features, and management visibility at this price point is genuinely transformative for SMEs.

We will give you a clear, detailed quote covering licences, hardware, setup, and ongoing costs. We compare options across multiple providers and recommend the best fit based on your specific requirements. No obligation, no pressure, just honest advice from an OFCOM-regulated team with 18 years of experience.

For more on VoIP technology and features, read our hosted VoIP for business guide or browse our business VoIP page for an overview of what we offer.

Get your free 20-user VoIP quote, it takes less than 2 minutes