When you switch from old phone lines to VoIP, you don’t just change the way you make calls-you change how your whole network behaves. The big question isn’t just which system is cheaper or which has more features. It’s this: how much bandwidth does your network actually need, and how does traffic flow through it? Cloud VoIP and on-premises VoIP handle this in completely different ways. One scales with a click. The other needs racks, wires, and careful planning. Let’s cut through the noise and see what really happens when calls go out over your internet.
How Much Bandwidth Do You Really Need?
A lot of people think VoIP needs tons of bandwidth. It doesn’t. Modern cloud VoIP systems use about 100 Kbps per call for high-quality audio. That’s less than a single HD video stream. If you have 20 people on calls at once, you’re looking at roughly 2 Mbps. Sounds simple, right? But bandwidth isn’t just about speed. It’s about consistency. Think of your internet connection like a highway. Bandwidth is the number of lanes. But if those lanes are full of trucks (downloads, backups, video calls), the cars (your VoIP calls) get stuck. That’s why connection stability matters more than raw speed. A 50 Mbps connection with jitter and packet loss will sound worse than a 10 Mbps line with clean, steady traffic. Cloud VoIP providers compress voice data efficiently. They use codecs like G.729 or Opus that trim down file sizes without killing clarity. On-premises systems can do the same-but only if they’re configured right. Many companies skip this step, then wonder why calls sound robotic or drop out.Who Controls the Traffic?
This is where the two models split wide open. With cloud VoIP, your traffic leaves your building and goes straight to the provider’s data center. That means you lose direct control over routing, prioritization, and congestion management. Your IT team can’t tweak the network path between your office and the provider’s server. You’re relying on their infrastructure, their QoS settings, and their peering agreements. But here’s the twist: they’re better at it than you are. Big cloud providers like Zoom, Microsoft Teams, and RingCentral have global networks built for VoIP. They use intelligent routing, multiple data centers, and real-time traffic analysis to keep calls smooth-even during spikes. If 500 employees suddenly start calling clients after a product launch? Their system absorbs it. No upgrades. No downtime. On-premises VoIP? You’re in charge. You can set up Quality of Service (QoS) rules to give voice traffic top priority over everything else. You can reserve bandwidth for your sales team, block video streaming during business hours, or route calls through a dedicated VLAN. If your network is well-designed, this gives you rock-solid call quality. But here’s the catch: most small and mid-sized businesses don’t have network engineers who know how to do this right. They set up VoIP, forget about QoS, and wonder why calls crackle when someone streams Netflix.Scalability: Clicks vs. Cables
Adding a new employee? With cloud VoIP, you log in, assign a number, and hit ‘activate’. Done. The system automatically adjusts bandwidth allocation. No hardware. No rewiring. On-premises? You need to buy another phone, plug it in, configure the PBX, update firewall rules, and maybe even upgrade your router if you’re out of ports. If you’re scaling up quickly-say, hiring 50 remote workers in three months-you’re either stuck waiting for gear or overpaying for unused capacity. And what about seasonal spikes? A retail business in Exeter might need 3x more calls during Christmas. Cloud VoIP handles it. On-premises? You either risk dropped calls… or you buy equipment sized for peak season, then pay to run it all year.Remote Workers and Distributed Teams
Let’s say you have employees working from Plymouth, Cardiff, or even Lisbon. With cloud VoIP, they just download an app. Their calls travel directly to the provider’s network-not through your office router. Bandwidth usage stays local to them. No VPNs. No complex tunneling. No extra load on your central network. On-premises? Every remote call has to tunnel back to your office. That means your office internet is now handling calls from 30 people across the UK. Suddenly, your 100 Mbps line is maxed out. You need a dedicated internet line just for VoIP. And if your office goes down? So does every remote worker’s phone.
What Happens When the Internet Goes Out?
This is the silent killer of cloud VoIP. If your internet dies, your phone system dies. No backup. No fallback. No exceptions. Even if your power stays on, no internet = no calls. On-premises systems can integrate with traditional phone lines (PSTN) or use cellular failover. Some even have battery backups and redundant internet connections. If your main line goes down, calls reroute through a backup DSL line or even a mobile hotspot. For businesses that can’t afford downtime-hospitals, emergency services, financial firms-this isn’t optional. It’s survival.Costs: Upfront vs. Ongoing
Here’s a quick comparison based on real-world figures as of 2026:| Item | Cloud VoIP | On-Premises VoIP |
|---|---|---|
| Initial Setup | $0-$1,500 | $8,000-$15,000 |
| 3-Year Ongoing Costs | $22,000-$40,000 | $3,000-$6,000 |
| Bandwidth Cost | Included in subscription | Separate internet bill |
| Hardware Maintenance | None | $500-$1,500/year |
| Power & Cooling | None | $300-$800/year |
Feature Updates and Traffic Tools
Cloud providers roll out new features every few weeks. Real-time analytics. AI-powered call routing. Automated QoS tuning. These tools help manage traffic patterns automatically. You don’t need to understand packet prioritization-you just enable the feature. On-premises? You wait for software updates from the vendor. Sometimes it’s once a year. Sometimes never. If you want advanced traffic shaping, you need to hire a specialist or buy expensive add-ons.
Which One Fits Your Business?
Ask yourself:- Do you have 10+ remote workers? → Cloud wins.
- Are you in an area with unstable internet? → On-premises with PSTN backup is safer.
- Do you have IT staff who can configure QoS? → On-premises gives you control.
- Are you growing fast or seasonal? → Cloud scales without delay.
- Is your network already overloaded? → Cloud VoIP reduces pressure on your local infrastructure.
Final Thought: It’s Not About the System. It’s About the Traffic.
Whether you choose cloud or on-premises, your network must handle voice traffic like a priority lane-not an afterthought. Both systems need QoS. Both need bandwidth monitoring. Both need someone watching the numbers. Cloud VoIP doesn’t eliminate network planning-it just moves it to the provider. On-premises doesn’t guarantee quality-it just puts the responsibility in your hands. The best choice isn’t the flashiest tech. It’s the one that matches your traffic patterns, your budget, and your risk tolerance.Does cloud VoIP use less bandwidth than on-premises?
No, the bandwidth per call is nearly identical-around 100 Kbps for both. The difference isn’t in how much data each call uses, but in how the network handles it. Cloud VoIP routes traffic through optimized provider networks, reducing strain on your local connection. On-premises VoIP sends all traffic through your office network, which can overload it if not managed properly.
Can I use VoIP with a slow internet connection?
You can, but call quality will suffer. VoIP needs consistent bandwidth, not just high speed. If your upload speed is under 1 Mbps and you have more than 5 users, expect lag, echo, or dropped calls. Test your connection with a tool like Speedtest.net during peak hours. If packet loss is over 1% or jitter exceeds 30ms, your internet isn’t ready for VoIP without QoS or a dedicated line.
Do I need a dedicated internet line for VoIP?
Not always, but it’s highly recommended. Sharing bandwidth with video streaming, file uploads, or cloud backups can ruin call quality. A dedicated line ensures VoIP traffic gets top priority without interference. Even if you use cloud VoIP, a separate connection for voice keeps your calls clear during heavy network use.
What’s the best way to prioritize VoIP traffic?
Set up Quality of Service (QoS) on your router. Assign the highest priority to traffic from your VoIP phones or softphones (usually identified by IP address or port number). Block non-essential apps like video streaming during work hours. For cloud VoIP, check if your provider offers a QoS guide-they often have recommended settings for common routers.
Can I switch from on-premises to cloud VoIP later?
Yes, but it’s not always easy. You’ll need to migrate phone numbers, reconfigure endpoints, and ensure your internet can handle the load. Many providers offer migration tools and support. Still, plan for downtime. A smooth transition requires testing, training, and a phased rollout-not just flipping a switch.
Is cloud VoIP secure for sensitive calls?
Yes, if configured properly. Leading providers use end-to-end encryption (TLS and SRTP), multi-factor authentication, and compliance with standards like GDPR and HIPAA. The bigger risk is your own network. If your Wi-Fi is unsecured or employees use personal devices without VPNs, the system is vulnerable. Cloud VoIP doesn’t remove security risks-it shifts them to your endpoint practices.
Next Steps
- If you’re considering cloud VoIP: Run a network test during your busiest hour. Check upload speed, latency, and packet loss. Contact three providers and ask for their recommended minimum specs.
- If you’re sticking with on-premises: Audit your current QoS settings. Are voice packets getting priority? Is your router old enough to support modern VoIP protocols? Budget for a hardware refresh every 4-5 years.
- Either way: Train your team. One employee streaming YouTube during a call can ruin quality for everyone.