SIP and VoIP: Understanding their Key Differences

Feb 7, 2025

Understanding the difference between SIP (Session Initiation Protocol) and VoIP (Voice over Internet Protocol) is crucial for businesses seeking efficient communication solutions. VoIP, introduced in the mid-1990s, enabled voice communication over the internet but lacked a standardized way to manage calls. SIP, developed later, addressed this by offering a flexible protocol to initiate and manage sessions for voice, video, and messaging. While VoIP provides the foundation, SIP is a signaling protocol that helps establish and manage multimedia communication over IP networks, including voice calls.. Understanding these technologies helps businesses make informed decisions for their communication systems.

In this blog, we’ll explore the key differences between SIP and VoIP, how each can benefit your business, and which solution may be best suited to your needs.

What is VoIP?

VoIP (Voice over Internet Protocol) is a technology that enables voice communication over the internet, as opposed to traditional telephone networks. Instead of relying on analog or digital phone lines, VoIP uses the internet to transmit voice data.

How VoIP works

VoIP converts voice signals into digital packets, which are transmitted over the internet to the destination. This process uses various protocols, including SIP, H.323, and others, to ensure that the call is properly established, managed, and terminated. The key to VoIP’s efficiency lies in its ability to transmit data over the same network used for internet traffic, reducing the need for separate infrastructure for voice communication.

Common use cases for VoIP

Personal communication: VoIP allows users to make voice calls over the internet, often using software like Skype, WhatsApp, or Google Voice.
Business communication: Businesses use VoIP to establish internal and external communication systems. VoIP enables flexible, cost-effective solutions for call centers, customer support lines, and remote teams.
Voice conferencing: VoIP is used to set up voice conferences, enabling communication across multiple parties, often with additional features like screen sharing and file sharing.

What is SIP?

SIP (Session Initiation Protocol) is a protocol used to initiate, maintain, and terminate communication sessions in a VoIP network. SIP is responsible for signaling the start of a call, routing the call through the appropriate network, and ensuring the communication remains stable throughout the session.

How SIP works

SIP operates at the application layer, handling call signaling and session management, while media transmission is managed by protocols like RTP(Real-time Transport Protocol). It works by establishing a session between two devices (such as a phone or a computer), routing the data packets, and ensuring the session is terminated when the call ends. SIP facilitates not only voice calls but also video conferencing, instant messaging, and presence notifications.

SIP is typically used in conjunction with VoIP. It provides the framework for initiating, routing, and terminating those calls.

Common use cases for SIP

Business phone systems: SIP is used to set up and manage corporate phone systems. It enables businesses to connect VoIP phones to the internet, facilitating cost-effective internal and external communication.
Unified communication: SIP is often used in Unified Communications (UC) systems that combine voice, video, instant messaging, and collaboration tools into one platform.
SIP Trunking: SIP trunking is used by businesses to connect their on-premise Private Branch Exchange (PBX) systems to the public switched telephone network (PSTN) using the internet, reducing the cost and complexity of managing multiple lines.

Key differences between SIP and VoIP

While SIP and VoIP are often discussed together, they serve different purposes within the communication ecosystem. Understanding the distinctions between them can help businesses make informed decisions when choosing communication systems.

Choosing the right solution for your business

Understanding SIP vs. VoIP is about recognizing that they serve different purposes but can work together seamlessly. SIP acts as a protocol that enhances VoIP by enabling multi-channel communication such as voice, video, and messaging.

VoIP as a foundation: Ideal for businesses that primarily need cost-effective voice communication without requiring advanced features. It’s easy to set up and manage, making it suitable for small to mid-sized organizations.
SIP for scalability and flexibility: Businesses looking for a comprehensive communication solution that integrates voice, video, and collaboration tools across multiple locations will benefit from SIP. It allows for easy scaling and works with existing VoIP systems to offer greater functionality.

Examples of VoIP and SIP in use

VoIP integration in an e-commerce platform

A global e-commerce platform utilizes VoIP for its customer support operations, allowing customers to call their support center from anywhere in the world at no additional cost. VoIP is integrated with the platform's CRM and order management systems, so when a customer calls in, the system automatically pulls up their account and recent purchase history. The integration allows support agents to resolve issues quickly, access shipping information, and issue refunds directly during the call.

Key details:

The e-commerce platform uses cloud-based VoIP to minimize infrastructure costs and scale effortlessly.
Real-time call analytics are integrated to optimize call routing and manage support queues based on agent expertise.
VoIP integration with AI-driven chatbots allows customers to initiate basic inquiries via voice or text, increasing first-call resolution rates.

SIP for unified communication in a distributed software development team

A global software development company uses SIP to streamline communications between its remote teams scattered across different continents. The company integrates SIP with their internal project management and code repository systems (such as GitLab and Jira), enabling secure voice, video, and chat sessions between team members without leaving the platform. This integration allows for seamless collaboration during daily standups, code reviews, and sprint planning meetings.

Key Details:

The SIP-based system is linked to video conferencing tools (such as Zoom or Microsoft Teams) for high-quality video calls and screen-sharing during meetings.
The system integrates SIP with presence management, automatically adjusting the team’s availability status based on the status of their work (e.g., “In meeting,” “Available,” “Do not disturb”).
End-to-end encryption for sensitive discussions about source code, combined with session expiration protocols, ensures that communications are secure and compliant with internal privacy regulations.
SIP enables dynamic routing for calls based on employee workload, ensuring that high-priority customer calls are always routed to the most available and qualified agent.

These examples highlight the versatility and power of VoIP and SIP in streamlining business communications. By implementing these technologies, companies can enhance collaboration, improve customer service, and increase operational efficiency.

How Plivo enhances communication with their voice API platform

Plivo’s Voice API Platform can help businesses take these capabilities to the next level. With Plivo, you can:

Conference call: Easily connect multiple participants using a conference bridge, allowing seamless group communications.
Alerts and notification: Dispatch customized audio alerts via voice calls to keep customers informed in real time.
Voice survey: Conduct surveys over voice calls, collecting valuable feedback directly from customers.
Voicemail: Capture important customer information while you're unavailable, ensuring no details are missed.
Scalable cloud IVR: Build multi-level IVR menus to route calls intelligently, improving customer service efficiency.
Call forwarding: Forward calls to alternate phones like your office or home, ensuring you're always reachable.
Global connectivity: Connect calls over the PSTN in over 200 countries, simplifying global communication without dealing with telecom complexities.
SIP gateway: Integrate and control your existing SIP infrastructure, adding advanced cloud functionalities.
SIP devices: Connect your existing SIP-enabled hardware and software phones, ensuring smooth integration with your communication systems.
Client SDKs: Embed native voice calling into your web or mobile apps, connecting users via any device or PSTN phone with minimal code.
Browser-based web application: Add high-quality VoIP calling to browser apps using Plivo’s WebRTC SDKs.
Mobile-based application: Integrate VoIP calling into iOS and Android apps with Plivo's mobile SDKs, optimized for battery life.

Plivo provides robust features, detailed call quality stats, and real-time monitoring tools to ensure seamless communication and quick issue resolution. With its scalable, cloud-based infrastructure, businesses can optimize voice communication, increase customer engagement, and boost overall efficiency.

Get started with Plivo today to enhance your business communications and streamline customer engagement across channels!