What is SIP trunking? Ultimate guide to business internet phone service

sip trunking

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Success in today’s hectic work environment is mainly dependent on efficient communication. However, traditional phone networks frequently can’t keep up with the needs of contemporary businesses. Businesses seeking cost-effectiveness, scalability, and flexibility are increasingly looking to SIP trunking as a solution to their communication problems. If you’re looking to maximise your corporate communication strategy, you’ve come to the right place.

Recent research by industry experts indicates that the worldwide SIP trunking market is expected to grow at a CAGR of 13.16% to reach US$31.401 billion in 2027 as companies from various industries realise how revolutionary it can be for their communication infrastructure.

However, what precisely is SIP Trunking, and how does it work with your company’s communication plan? This thorough guide addresses all of these concerns and more, offering insightful knowledge on SIP trunking and how it will influence business communication in the future.

What is SIP trunking?

SIP trunking is a technique for providing voice and other unified communications services via the Internet using the Session Initiation Protocol (SIP). It allows companies to use the Internet to link their Private Branch Exchange (PBX) and place and receive calls instead of traditional phone lines.

Unlike traditional phone systems that rely on physical lines, Session Initiation Protocol trunking operates over the Internet, enabling seamless connectivity and communication between devices to combine their phone and data services. By leveraging the flexibility of IP networks, SIP trunking increases productivity and reduces costs.

Benefits of SIP trunking

Businesses looking to empower their workers and optimise their communication infrastructure might benefit immensely from SIP Trunking. SIP trunking provides a variety of benefits to companies wishing to update their communication infrastructure. They are:

  1. Cost Savings: SIP trunking is generally less expensive than traditional phone lines, particularly for long-distance and international calls. Businesses can lower infrastructure costs by combining data and voice into a single network infrastructure with SIP.
  2. Scalability: SIP trunking makes it simple for companies to adjust their communication capacity according to their demands. Businesses that experience seasonal peaks in call numbers or changing call volumes may benefit most from this scalability.
  3. Flexibility: SIP trunking supports various communication features such as voice, video, and instant messaging. For a more unified and effective communication system, users can also combine SIP trunking with other communication tools like Unified Communications (UC) systems.
  4. Advanced features: SIP trunking supports interactive voice response (IVR) systems, caller ID, call forwarding, voicemail, and other advanced communication capabilities. These characteristics facilitate internal communication inside the company, increase efficiency, and improve customer service.
  5. Integration with Existing Infrastructure: SIP trunking can be easily integrated with current PBX (Private Branch Exchange) systems and equipment, enabling companies to maximise their communication technology investments while switching to a more advanced and affordable solution.

How does SIP trunking work?

SIP trunking works by using the internet to deliver voice communication services, thereby substituting traditional phone lines with SIP-enabled virtual connection. A set number of call channels—virtual phone lines—are assigned by the provider to a business that subscribes to SIP trunking service. The business phone system, known as the IP PBX system, is set up to establish an internet connection with the SIP provider’s network in order to handle and route calls.

working principle of sip trunking

The SIP protocol, which is responsible for starting, maintaining, and ending communication sessions, is used to establish this connection. When a caller from outside the firm calls the company, the SIP provider answers and transfers the call to the business’s IP PBX via the Internet.

The PBX routes the call to the appropriate internal extension, ensuring that it reaches the intended party within the company. On the other hand, outbound calls are routed from the IP PBX to the SIP provider when a corporate employee calls a non-internal number.

It then connects this call to one of the Internet telephony service providers of the telephony network. By adding or removing call channels as needed, this smooth routing process enables businesses to maintain strong communication capabilities without the need for traditional phone lines. This allows for flexibility and scalability and may result in lower costs, particularly for long-distance and international calls.

SIP trunking vs. PRI

SIP trunking and Primary Rate Interface (PRI) are both methods of connecting a Private Branch Exchange (PBX) to the Public Switched Telephone Network (PSTN), but they differ in technology, scalability, flexibility, and cost.

SIP trunking provides more flexibility in terms of adding or removing channels as needed. It uses the Session Initiation Protocol (SIP) to create virtual connections via an internet connection. Because it uses already-existing internet infrastructure and provides scalability without requiring extra physical lines, it is usually more affordable.

On the other hand, PRI is a specialised digital circuit that needs a different physical connection to the PSTN and offers a set number of channels (often 23) for voice calls. Although PRI guarantees call quality and dependability, it is less flexible and scalable than SIP trunking, which means that enterprises must frequently buy more channels in predetermined increments.

SIP trunking is a more adaptable solution for contemporary communication needs since it may enable a range of communication services in addition to audio, such as video conferencing and instant messaging.

SIP trunking vs. VoIP

Voice over Internet Protocol, or VoIP, is a technology that allows voice calls to be sent over the Internet as opposed to regular phone lines. For the purpose of converting, packetising, and transferring voice data over IP networks, it includes a variety of protocols and technologies that enable phone calls, video calls, and multimedia conferencing, among other communication applications.

In contrast, SIP trunking is a particular VoIP technology implementation designed to connect private branch exchange (PBX) systems to the public switched telephone network (PSTN) online. SIP trunking is a service that eliminates the requirement for conventional analogue or digital phone lines by creating virtual connections, or trunks, between the PBX and the service provider network using SIP as a signalling protocol. By enabling companies to use their current PBX infrastructure to make and receive phone calls via the Internet, this technology provides cost savings, scalability, and flexibility.

In summary, SIP trunking is a specific VoIP application designed for business telephony needs, providing increased efficiency and flexibility, whereas VoIP as a whole encompasses voice communication via IP networks.

Future Trends in SIP Trunking

SIP trunking will play a pivotal role in shaping enterprise communication as businesses adapt to the evolving landscape of communication technology. Several key trends are expected to drive the growth and evolution of SIP trunking in the coming years:

  1. Market Boom: The SIP trunking industry is expected to develop significantly and surpass $30 billion in revenue by 2027. Businesses are recognising the cost-effectiveness, scalability, and flexibility that SIP trunking offers, which is causing this rise.
  2. Cloud Integration: Platforms for cloud-based communication are becoming increasingly popular. While we would not be able to combine the features of these online services, SIP trunking is expected to merge and form a full communications solution that goes beyond physical boundaries.
  3. Remote and Hybrid Work Friendly: As remote and hybrid work models become the norm, SIP trunking will change to meet these changing needs. This includes components that guarantee seamless communication for geographically dispersed workers.
  4. Security Focus: SIP trunking providers will continue to emphasise security as cyber threats become more complex. Cybersecurity advancements will be essential for secure and dependable communication.


SIP trunking is a game-changing technology that allows companies to improve flexibility, cut expenses, and accelerate communication. Companies in various industries are seeing the potential of SIP trunking to completely transform their communication infrastructure, as the global market for this technology is growing at an accelerated rate.

Due to its affordability, scalability, and integration opportunities, SIP trunking has the potential to influence how corporate communication is shaped in the future. Including SIP trunk service in your corporate communication plan guarantees that your company will always be competitive, flexible, and ready to take on new challenges in the digital era.

Upgrade your communication infrastructure using SIP trunking and pave the way for enhanced productivity, cost savings, and future growth. Contact us to find out more and start your path to increased communication effectiveness.



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