SIP vs VoIP: What Are They and How Do They Differ?

Despite serving as the popular default mode of communication for a long time, traditional phone lines are exhibiting declining popularity today, largely due to their high cost and limited flexibility.

A fairly recent BBC report reveals that landline usage dropped by 40% among various age groups, with more than half the under-25 respondents saying they never bothered getting a landline installed at all.

Voice over Internet Protocol (VoIP) technology has advanced communication to new heights, providing businesses with a more affordable, feature-rich, and high-quality voice communication option. Closely connected to this technology is Session Initiation Protocol (SIP) trunking. Both use the internet to make phone calls, but they differ in features and functionality.

To figure out which one would fit their unique requirements and budgets, businesses need to understand the differences between SIP vs VoIP.

This article explores the features, benefits, and constraints of SIP and VoIP, taking a closer look at these technologies and how they can work together to deliver an optimal voice experience.

What is SIP trunking?

SIP trunking uses a signaling protocol called the Session Initiation Protocol (SIP) to enable the delivery of unified communications, such as voice, video, and instant messaging, over the internet. The session initiation protocol is used for handling multimedia communications such as voice and video calls, conferences, chats, and more. SIP primarily manages, sets up, and terminates the sessions for these communications.

SIP trunking allows businesses to replace traditional telephone lines with an internet-based phone service, connecting an organization’s internal phone system directly to the public switched telephone network (PSTN) via the internet.

How does SIP work?

SIP does not transmit multimedia information itself; it only manages its flow. It uses other protocols, such as RTP (real-time transport protocol) or SRTP (secure real-time transport protocol), to transmit voice data. While SIP initiates, maintains, and terminates sessions, these other protocols handle the actual transfer of voice or video data.

What is VoIP telephony?

Voice over Internet Protocol (VoIP) is a collective term that covers technologies that allow voice data to be transmitted over IP networks. VoIP encompasses a set of standards and specifications that define how voice communication over IP should occur. It enables users to make phone calls using a broadband internet connection instead of a traditional analog phone line.

VoIP can turn any internet connection into a phone line, allowing for voice communications through computers, VoIP phones, or even traditional phones with special adapters.

How do VoIP calls work?

The fundamental mechanism behind VoIP technology involves transforming analog voice signals into digital data. The internet then transmits these packets, which are reassembled at their destination. VoIP systems can interconnect with the traditional phone network, allowing voice calls between VoIP users and regular phone users.

It’s important to remember that SIP is one of the protocols that a VoIP setup can use. People often use the term VoIP in everyday conversation to refer to specific voice over IP solutions that may differ from SIP. For example, Skype, Viber, and WhatsApp are examples of VoIP services that use their own independent proprietary protocols for voice over IP communication.

6 main differences between SIP and VoIP

SIP calls and VoIP have their advantages and disadvantages, and the choice between the technologies depends on your needs and capabilities. Let’s explore the key differences.

1. Main function

SIP is primarily a session establishment protocol responsible for initiating, maintaining, and terminating communication sessions. It handles the signalling aspects of a call, such as ringing, modification, and termination. VoIP, in contrast, is a broader technology that encompasses the entire process of transmitting voice data over IP networks, including the actual transfer of audio packets and multimedia data using relevant protocols.

2. Equipment requirements

For both SIP and VoIP services, you would need the right subscriber devices, such as IP phones or IP PBX systems. The main difference is in the software and protocols that those devices use. SIP devices must specifically support the SIP protocol, while VoIP devices could use a variety of protocols, including but not limited to SIP.

3. Availability and cost

Both SIP and VoIP technologies themselves are generally free of charge. The implementation and service costs may vary, though, depending on the provider and the specific solutions chosen.

4. Sound quality

Both SIP and VoIP can offer high-quality audio. The sound quality actually depends more on other factors, such as internet connection speed, network capacity or congestion, and codecs used, rather than on whether you’re using SIP or VoIP.

5. Mobile and international calls

While SIP itself doesn’t inherently support mobile calls, many modern VoIP applications and services integrate SIP to enable mobile phone functionality. Because VoIP is a broader technology, it naturally includes mobile calling capabilities. Both SIP and VoIP support international calls, with cost-effectiveness being one of the major advantages of internet-based phone services over traditional phone lines.

6. Additional features

SIP has limited additional features, but it is possible to extend many SIP-based systems to support a wide range of functionalities. VoIP systems typically come with a plethora of built-in features, such as call recording, call forwarding, voicemail-to-email, interactive voice response (IVR) systems, and more. The exact feature set you get depends on the specific VoIP service or solution you employ.

SIP vs VoIP: Quick summary

The pros and cons of using VoIP technology on its own

Using VoIP technology for your voice communication needs can have its ups and downs.

The advantages of VoIP

With a VoIP system, you can greatly optimize your costs, particularly for long-distance and international calls.

Another advantage is that users can make calls from a variety of devices with an internet connection, giving them quite a bit of freedom.

On top of that, VoIP systems frequently include sophisticated features that improve business communication, such as conference calling, voicemail-to-email, and call forwarding.

The disadvantages of VoIP

A strong internet connection is necessary for VoIP. Unreliable or poor connections can cause dropped calls and poor call quality, leading to a terrible experience. Also, compared to traditional phone lines, some VoIP providers might not be able to handle emergency calls as reliably.

Another downside is that since VoIP communications are transmitted via the internet, they are vulnerable to interception if appropriate encryption is not used. This raises some security concerns.

VoIP-only systems may not work with outdated gear or software. VoIP phones might not work during blackouts unless they have a backup power supply.

Lastly, even though VoIP has a lot of functions, organizations without specialized IT staff may find it difficult to manage and maintain a VoIP-only system.

The advantages of making VoIP calls with SIP

If you decide to use VoIP along with SIP trunking for your business phone system, it will open you up to some amazing benefits.

• With SIP, you will get a simplified beginning, middle, and end for all calls.

• The flexibility and scalability that SIP offers will make it easy to grow and modify your VoIP system.

• You will get functions like call forwarding and video conferencing.

• You can integrate several communication services into a single connection, helping you cut costs.

• SIP can facilitate VoIP on a range of devices, augmenting portability. Plus, it works well with a variety of VoIP tools and services, making integration and interoperability a breeze.

• You get better options for authentication and encryption.

Choosing the right technology for voice calls

VoIP technology supported by SIP trunking offers businesses a cost-effective and feature-rich solution for voice calls. It provides high-quality audio, mobility through various devices, and competitive international rates. In certain cases, if you make a lot of international or inter-network calls, you can get free or low rates with VoIP.

Consider your call volume, feature needs, and budget to decide if VoIP, or VoIP with SIP trunking for advanced features, is the right fit for your company.

Decision Telecom offers simple and affordable voice-calling solutions for businesses around the world.

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