A business’s phone system is only as good as the network powering it.
The combination of distributed workforces, industry consolidation, and the need to scale means IT leaders are re-evaluating their phone systems to ensure they meet the demands of modern workflows.
Traditional Voice over Internet Protocol (VoIP) is still a reliable choice for many companies as it offers flexibility, cost savings, and high-quality performance for organizations of all sizes.
Despite this, selecting a reliable VoIP service provider is crucial for effective communication over the Internet. It ensures a stable, high-speed connection and supports key features like HD video and team collaboration.
This guide will show you the exact steps you can take to build a robust VoIP architecture that’s tailored to your company’s needs, including:
The basics of VoIP architecture in Internet Protocol (IP) networks
Key components of VoIP architecture
How VoIP networks transmit data
Common VoIP protocols
How to plan your VoIP architecture
Common VoIP deployment scenarios from the field
What is VoIP Architecture in an IP Network?
VoIP architecture provides the framework for delivering real-time voice and multimedia communications over an internet connection.
Unlike traditional phone systems reliant on physical lines, VoIP transmits voice as digital data packets across IP networks.
The performance of a VoIP system hinges on three critical factors:
Network Stability: Ensuring consistent, uninterrupted communication.
Security: Protecting data and calls from external threats.
Cost-Effectiveness: Leveraging existing internet infrastructure to reduce costs.
Modern VoIP protocols like Session Initiation Protocol (SIP) and H.323 enable the setup, management, and termination of calls, making VoIP systems scalable, secure, and efficient.
Additionally, the call control function within the Signaling Gateway Controller (SGC) is essential for connecting traditional analog call services to digital voice calls, supporting both signaling and media call control protocols.
Why choose VoIP for your business?
There are many reasons why businesses are shifting to VoIP. Some of the most notable benefits include:
Cost Savings: Reduced costs compared to traditional landlines.
Scalability: Adaptable to your business’s size and growth.
Flexibility: Compatible with a variety of devices—from desk phones to mobile apps.
Advanced Features: Call forwarding, video conferencing, voicemail-to-email, and more.
To build a robust VoIP system, understanding its architecture is essential.
Next, we’ll explore the key components that make VoIP work seamlessly.
Key components of VoIP architecture
A well-designed VoIP system includes several components that work together to ensure efficient, high-quality communication.
1. Session Border Controller (SBC)
The SBC serves as a gateway that connects VoIP systems to external networks, such as the Public Switched Telephone Network (PSTN). It manages:
Call control functions
Traffic balancing
Bandwidth optimization
Network security
Bandwidth management control to optimize traffic flow and maintain superior service quality
2. Application Server
The application server provides the backend services, applications, and logic needed to manage and enhance VoIP. It acts as the middle layer between VoIP endpoints and network infrastructure, enabling advanced features beyond simple calling. These advanced features include:
Call forwarding and transfer
Call waiting
Voicemail
Detailed call records
Media processing
Authentication and authorization
3. Endpoint Devices
Endpoint devices are the physical or digital tools your team uses to communicate. Popular examples include:
Desk phones
Softphone applications (VoIP apps on desktops and smartphones)
Conference phones
Fax machines with VoIP adapters
4. SIP Services
SIP plays a foundational role in VoIP systems by establishing, modifying, and terminating calls. They also support voice, video, and messaging technologies.
SIP infrastructure consists of several components, including:
SIP proxy servers
SIP registrar server
SIP redirect server
SBCs
5. Media Server
The media server manages voice and data traffic. It handles essential tasks like voice and signal processing, voicemail storage, and enabling video calls and conferencing.
6. Database Services
Database services store and manage endpoint registrations, user information, IP addresses, and address translations across networks. IP addresses play a crucial role in identifying and registering devices in VoIP systems, allowing devices to locate each other and communicate effectively.
7. IP PBX (Private Branch Exchange)
The IP PBX acts as the control center for managing internal and external communications. It connects VoIP endpoints to SIP trunks, enabling seamless call routing.
8. IP Network
Your IP network serves as the backbone of your VoIP system, enabling voice data packets to flow between devices and upstream services. A stable, optimized network is crucial to ensuring clear, reliable communication.
How VoIP works: Voice data packets
Unlike traditional landlines, VoIP converts analog audio signals into digital packets using gateways or codecs. These packets are sent across IP networks — local area networks (LANs), wide area networks (WANs), or the Internet — and reassembled at the destination to deliver high-quality audio.
Here’s a simplified process of how VoIP works:
Signal Conversion: Voice signals are digitized at processing nodes (gateways/codecs).
Packet Transmission: Data packets travel across the IP network to their destination.
Reassembly: Packets are reassembled into clear, audible audio.
To ensure high-quality communication, it’s critical to optimize and prioritize voice packets. Features like Quality of Service (QoS) ensure voice data gets priority over other network traffic, minimizing delays and disruptions.
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Common VoIP protocols
VoIP protocols are the set of rules that govern how devices initiate, manage, and terminate voice calls over the internet.
These protocols ensure that voice data packets are transmitted efficiently and reliably across IP networks.
The most common VoIP protocols include Session Initiation Protocol (SIP), H.323, and Real-Time Transport Protocol (RTP).
Session Initiation Protocol (SIP): Widely used due to its simplicity, flexibility, and ability to integrate seamlessly with other internet protocols. SIP is responsible for establishing, modifying, and terminating VoIP calls, making it a cornerstone of modern VoIP systems. Its versatility allows it to support not just voice, but also video and messaging technologies.
H.323: Another popular protocol that provides a comprehensive framework for multimedia communication over IP networks. It is known for its robustness and ability to handle complex communication scenarios, making it suitable for large-scale deployments.
Real-Time Transport Protocol (RTP): Used for transporting real-time audio and video streams over IP networks. RTP ensures that voice and video data are delivered in a timely manner, maintaining the quality and synchronization of the media streams.
By leveraging these VoIP protocols, businesses can ensure efficient, high-quality communication across their networks.
How to plan your VoIP architecture
Building a successful VoIP system requires careful planning.
Consider these key questions as you design your architecture:
Growth Projections:
Where will your company be in 1 year?
How many employees will you have?
How much growth are you projecting?
Remote Work Requirements:
Will your workforce be remote, in-office, or hybrid?
What tools and devices do remote employees need?
Feature Priorities:
What VoIP features are essential for your operations? (e.g., video conferencing, voicemail-to-email, call routing)
Bandwidth Needs:
How much bandwidth is required for simultaneous calls, video conferencing, and other activities?
Have you implemented QoS to prioritize VoIP traffic?
By addressing these questions, you can design a VoIP architecture that scales with your business and meets current and future demands.
include Session Initiation Protocol (SIP), H.323, and Real-Time Transport Protocol (RTP).
Session Initiation Protocol (SIP): Widely used due to its simplicity, flexibility, and ability to integrate seamlessly with other internet protocols. SIP is responsible for establishing, modifying, and terminating VoIP calls, making it a cornerstone of modern VoIP systems. Its versatility allows it to support not just voice, but also video and messaging technologies.
H.323: Another popular protocol that provides a comprehensive framework for multimedia communication over IP networks. It is known for its robustness and ability to handle complex communication scenarios, making it suitable for large-scale deployments.
Real-Time Transport Protocol (RTP): Used for transporting real-time audio and video streams over IP networks. RTP ensures that voice and video data are delivered in a timely manner, maintaining the quality and synchronization of the media streams.
By leveraging these VoIP protocols, businesses can ensure efficient, high-quality communication across their networks.
Common VoIP deployment scenarios
VoIP deployment scenarios vary depending on the size and complexity of the organization.
Here are two common deployment scenarios we see all the time.
1. Single Office
This deployment scenario is relatively simple and easy to manage.
It involves setting up VoIP phones and ensuring that the network infrastructure can handle the voice data packets efficiently. However, it may not be suitable for organizations with multiple locations or remote employees, as it lacks the flexibility to support diverse communication needs.
2. Multiple locations and remote employees
In a multiple locations and remote employees deployment scenario, employees are spread across different physical locations, and some may work remotely.
This scenario requires a more complex VoIP system that can handle multiple IP networks, various internet service providers, and remote connections.
The system must be capable of prioritizing voice traffic to ensure high-quality voice calls, even when network traffic is high. Advanced features like call forwarding and video conferencing become essential to maintain seamless communication across the organization. This deployment scenario provides the flexibility and scalability needed to support a distributed workforce.
Public switched telephone network (PSTN) integration
PSTN integration is the process of connecting a VoIP system to the traditional public switched telephone network (PSTN). This integration allows VoIP users to make and receive calls to and from traditional landline and mobile phones, bridging the gap between modern VoIP systems and legacy telephone networks.
PSTN integration is typically achieved through a media gateway or a session border controller (SBC). The media gateway converts VoIP calls into traditional PSTN calls, ensuring compatibility between the two systems. It handles the conversion of voice data packets into the analog signals used by the PSTN, enabling seamless communication.
The session border controller (SBC) provides additional security, routing, and signaling functions. It acts as a gatekeeper, managing the flow of voice data between the VoIP system and the PSTN. The SBC ensures that calls are routed correctly and securely, protecting the network from potential threats.
PSTN integration is essential for organizations that need to communicate with customers, partners, or suppliers who use traditional phone systems. It ensures that VoIP users can reach any telephone network, enhancing the flexibility and reach of the VoIP system.
The importance of bandwidth management control
Bandwidth plays a pivotal role in call quality. To ensure high-quality VoIP phone service, proper bandwidth management is essential.
A single VoIP call requires approximately 100 kilobits per second of bandwidth. Multiply this by the number of simultaneous calls to estimate your bandwidth requirements.
Additional activities such as file backups, video conferencing, and large data transfers will increase your overall needs. To maintain high-quality calls:
Prioritize voice traffic with Quality of Service (QoS) settings.
Optimize your network infrastructure for peak performance.
Monitor and manage bandwidth usage regularly.
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Access reliable VoIP solutions for your business
Building a successful VoIP architecture requires careful planning, the right components, and a strong network foundation.
By understanding your company’s communication needs, growth trajectory, and infrastructure, you can implement a VoIP system that enhances efficiency and scales with your business.
For businesses looking to take the next step, Momentum offers the expertise and support needed to optimize your communication systems. Whether you’re evaluating new options or upgrading your existing VoIP network, work with a partner that has deep knowledge and reliable solutions can make all the difference.
Have questions about VoIP implementation? Contact us to learn more.
Interested in exploring your options? Speak with one of our Microsoft Teams AI experts today to learn more.
