Quality of Service, or QoS, is a method used in networking to make sure time-sensitive services like phone calls, video meetings, and cloud communication work smoothly without interruptions.
If you are a business in Ireland struggling with unstable VoIP audio or jittery calls, QoS is the technology that prevents these issues.
What Is QoS (Quality of Service)?
Quality of Service, often written as QoS, is a network feature that controls how data flows across your internet connection. Instead of letting every device fight for network resources, QoS ensures important tasks such as phone calls, real-time communication, and business-critical systems get priority.
Without QoS, all network traffic is treated equally, which leads to congestion during busy periods. QoS protects time-sensitive data, so calls do not break, lag, or distort.
How Quality of Service (QoS) Works?
- QoS works by identifying the type of traffic that passes through your network.
- Voice traffic is classified using markers such as Differentiated Services Code Point (DSCP), placed within the packet header of each voice packet.
- Once identified, the network gives this traffic a higher priority so it travels quickly through routers, switches, and other network devices.
- This ensures predictable performance even when your business’s internet is busy.
Why is QoS Important for VoIP & Video Conferences?
1. Prevents Delays and Voice Overlap
QoS ensures voice packets are delivered instantly. Without it, even a 150ms delay creates echo, robotic voices, and people speaking over each other.
2. Reduces Jitter and Packet Loss
Congested networks cause jitter Common Problems QoS Solves and lost packets. QoS keeps VoIP packets in order, preventing choppy, distorted, or broken audio.
3. Stops Other Apps from Interrupting Calls
Streaming, cloud backups, and software updates can overload the network. QoS restricts them, so your calls stay clear and stable at all times.
4. Essential for Video Meetings
Teams, Zoom, and cloud-based phone systems rely on real-time traffic. QoS ensures smooth audio and video, avoiding freezing or lag.
5. Prevents Dropped Calls
Routers without QoS discard packets when traffic spikes. VoIP cannot repair missing packets, causing dropouts. QoS protects packets so calls stay connected.
6. Improves Overall Communication Quality
By prioritising real-time traffic, QoS guarantees professional, reliable communication across all devices and platforms.
Types of QoS
1. Priority Queuing (PQ)
Priority Queuing places voice packets at the very top of the processing queue. All real-time traffic moves first, ahead of every other type of network traffic, reducing latency and jitter instantly.
2. Weighted Fair Queuing (WFQ)
Weighted Fair Queuing divides bandwidth fairly across multiple types of traffic while still giving VoIP more weight. It prevents heavy applications from starving voice traffic during peak usage.
3. Class of Service (CoS)
Class of Service applies prioritisation at the network switch layer. It tags voice traffic at Layer 2, improving performance within local networks before traffic reaches the internet connection.
4. Differentiated Services (DiffServ)
Differentiated Services uses DSCP values within the packet header to classify and prioritise voice traffic across routers and firewalls. It is widely used because it supports scalable and flexible QoS policies.
5. MPLS QoS
MPLS QoS prioritises traffic across private carrier networks. It provides end-to-end performance guarantees, especially for businesses with multiple sites, ensuring VoIP stability between offices.
Common Problems QoS Solves
Businesses often face call quality issues without understanding what causes them. The most common issue is congestion. When multiple people download large files or stream content, the network becomes clogged. VoIP packets then wait behind other traffic, causing jitter and audio drops. QoS solves this by reorganising the queue.
Another common problem is packet loss. When a network becomes overloaded, routers discard packets to free resources. Data apps can recover from this, but VoIP cannot. Missing audio packets translate directly into gaps or robotic sound. QoS guarantees low packet loss by safeguarding voice packets.
Delays also cause major disruptions. When latency increases, conversations feel out of sync. With QoS enabled, latency remains stable because voice traffic receives priority routing. This improves day-to-day operations for teams using cloud telephony or softphones.
Best QoS Settings for VoIP (Recommended Configurations)
1. Correct DSCP Marking
Use DSCP 46 (Expedited Forwarding) for voice packets to give them the highest priority. SIP signalling traffic normally uses DSCP 24 or 26. These markers help routers instantly recognise VoIP traffic and handle it ahead of other data.
2. Minimum Bandwidth per Call
Reserve at least 100–150 kbps for every VoIP call. This ensures each call stays clear and stable, even when multiple users or cloud-based systems share the same internet connection.
3. Set an Effective Jitter Buffer
Configure a jitter buffer between 20–30 ms. This allows the system to absorb small variations in packet timing and prevents robotic or broken audio during conversations.
4. Correct SIP & RTP Port Configuration
Ensure firewalls and routers have the required SIP and RTP ports open and properly routed. This avoids audio drops, one-way audio, or calls that fail to connect internally.
5. Apply Rate Limiting to Heavy Traffic
Limit or throttle non-essential activities such as cloud backups, large downloads, software updates, or media streaming. Rate limiting prevents these actions from consuming the bandwidth needed for voice calls.
How to Enable QoS on Your Network?
1. Accessing Network Equipment
Many enable QoS through their router or firewall interface. Most network devices include QoS features within advanced settings, where traffic types can be identified and prioritised.
2. Identifying VoIP and Cloud Telephony Traffic
A review of the applications, SIP ports, and RTP ranges associated with VoIP is required. Once identified, this traffic is flagged so network devices recognise it as high-priority, time-sensitive data.
3. Assigning High-Priority Classification
Voice packets are marked to ensure routers handle them before general traffic. This classification maintains smooth communication even during busy network periods.
4. Allocating Guaranteed Bandwidth
A dedicated portion of network bandwidth is reserved for voice. This ensures calls remain stable while preventing other activities from consuming essential capacity.
5. Isolating Voice Using VLANs (For Larger Networks)
Some organisations use separate VLANs to isolate voice traffic from data traffic. This keeps phone systems predictable and reduces the impact of heavy usage on overall call quality.
6. Monitoring and Fine-Tuning Performance
Once QoS is active, continuous monitoring is required. Adjustments may be needed based on how the team uses cloud tools, CRM systems, softphones, or remote-work applications.
7. Ongoing Review and Maintenance
QoS is not a set-and-forget configuration. Network environments evolve, so periodic evaluation ensures performance stays consistent as business needs grow.
Best Practices to Maintain QoS in Business Environments
Maintaining QoS requires the right network infrastructure. Consumer-grade routers rarely support advanced features, so using business-grade equipment ensures stable performance. Ensure firmware updates are applied regularly to keep network security and performance stable. Monitor network behaviour weekly to spot unusual spikes.
Limit heavy downloads during peak business hours. Schedule cloud backups or software updates outside working time. Apply traffic shaping rules to keep the network consistent. Always review QoS settings after adding new staff or expanding to multiple locations. Networks evolve, and QoS policies must evolve with them.
How SystemNet Optimises QoS for Irish Businesses
SystemNet Communications is a long-standing cloud-based telephone systems and VoIP provider in Ireland. Our role is to help businesses understand their network behaviour, identify congestion points, and ensure voice traffic moves smoothly through their infrastructure.
We analyse routers, switches, and traffic patterns, then apply tailored QoS configurations that protect time-sensitive communication. With continuous monitoring and refinement, organisations gain clearer calls, stable performance, and reliable connectivity across their cloud telephony environment.
Get Professional Support
If your organisation requires reliable cloud telephony with professional-grade performance, at SystemNet, our networking experts can guide you with the right information so you can make an informed decision.
Speak with an expert to understand how QoS can support your communication needs.
Final Thoughts
QoS is not a luxury; it is essential for any organisation relying on VoIP or cloud communication. Without it, your network struggles to deliver real-time audio. With it, communication becomes stable and dependable.
By understanding how QoS works, you can choose better systems, avoid disruptions, and support business-critical operations.
FAQs
Q. Do I need QoS for VoIP even with high-speed broadband?
Yes, speed alone cannot protect calls from jitter, congestion, or packet loss during busy network periods.
Q. Can QoS fix jitter completely?
QoS significantly reduces jitter by prioritising voice packets, but your physical connection must also remain stable and well-maintained.
Q. Is QoS required for softphone users?
Yes, because softphones depend heavily on consistent network performance across laptops and Wi-Fi connections.
Q. Does QoS increase internet speed?
No, QoS reorganises traffic to protect real-time services but does not increase actual broadband speed.
Q. Will QoS help with video conferencing?
Yes, video platforms benefit from prioritised traffic, reducing freezing, lag, and audio-video desynchronisation.
Q. Does QoS work on Wi-Fi?
Yes, but results vary depending on router quality and signal strength. Wired connections always perform better.
Q. Is QoS a security feature?
No, QoS improves performance, not security. Firewalls still handle protection.
Q. Do remote workers benefit from QoS?
Yes, home routers can prioritise softphone traffic to improve call quality significantly.
Q. Is QoS difficult to configure?
QoS requires expertise because settings must match your VoIP system, routers, and bandwidth patterns.
Q. Does QoS work for multi-site businesses?
Yes, especially with MPLS or well-designed SD-WAN, where end-to-end prioritisation is required.