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What is a SIP Trunk?

What is a SIP Trunk?

What is a SIP Trunk?

Learn everything you need to know about SIP Trunks and SIP Trunking

Anybody who has shown an interest in Voice over IP (VoIP) or business phone systems, will very likely have come across the term SIP trunk. But what does the term mean, what does SIP stand for, what does a SIP trunk do and how does it work? This article will answer all these questions as well as going into more detail regarding why businesses should use SIP trunking, how your business can benefit from the technology as well as looking at any possible downsides to SIP trunking.

1. What is a SIP Trunk?

A SIP Trunk is a telephone connection for businesses. SIP trunks and SIP trunking are now the standard method of connecting a business’ phone system (PBX - Private Branch Exchange) to the telephone network. In simple terms, SIP trunking allows a business phone system to work via an Internet connection as opposed to traditional phone lines.

Any business with a modern business phone system, i.e. an IP PBX (a PBX that supports using SIP for voice and data transfers), will also require a way for the phone system to connect to the Public Switched Telephone Network (PSTN). Until recently, this was done using ISDN. However, many countries have already shutdown their ISDN networks and others, like the UK, are in the process of doing so. As a result, SIP trunks have become more mainstream and are now the industry standard option for connecting business telephony networks via the internet.

But what is SIP and what is a trunk and how do they work?

2. How SIP Trunking works

Before we go into the benefits of SIP trunking, let’s first take a look at SIP and how SIP trunks actually work.

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SIP stands for Session Initiation Protocol and handles the setup and termination of communication sessions (voice, video, data, … etc.) over IP-based (Internet Protocal)networks, such as the Internet.

A trunk is the traditional name given to the point where all your business phone lines are bundled together so that they can function correctly. Since the move to digital communications, modern trunking now refers to a virtual link between the provider and your phone system (PBX) and is in fact a collection of assigned “channels”, with each channel handling a certain number of concurrent calls.

SIP trunks, also often referred to as SIP trunking, are the digital alternative to traditional analogue telephone lines. SIP trunks are “connected” to your business phone system (PBX) and transmits all your voice calls over your Internet connection. As everything runs over the Internet, physical phone line limitations are removed, making it possible to connect a flexible number of SIP channels to your business communications platform.

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3. What are the benefits of SIP Trunking

Looking beyond the obvious benefits of modernising your business and ticking off another box on your digital transformation checklist, there are many benefits of SIP trunking that you should be aware of.

Streamline network & infrastructure requirements

Until recently, it was normal practice for businesses to maintain separate networks for Voice and for Data. This practice was time and resouce intensive. As SIP converts voice to data packets, businesses are able to combine voice and data into a single network which in turn reduces the capital and resources required for network maintenance.

Moreover, SIP significantly reduces your infrastructure requirements and helps improve your business’ agility when reacting to changes in requirements. For example, in the past, moving to or connecting a new office location involved long wait times as businesses had to wait for the their telecoms provider to implement the changes required. Furthermore, SIP makes connecting remote workers much simpler because all that is required by remote/home office employees to make and receive calls on their office extension need is an Internet connection, their laptop and/or smartphone.

Scalability and Reach

SIP Trunking also offers considerable benefits when it comes to scalability. Firstly, ISDN and E1/T1 connections only allow between 2 and 30 voice channels whereas SIP trunks allow an almost limitless number of channels.

Secondly, adding new SIP trunks is straightforward and involves next to no lead time, meaning as your business grows, so too can your SIP trunking solution which ensures your customers can always reach you.

Next, as SIP trunks utilise IP networks to combine voice and data transmissions, they are not tied to a physical location, SIP trunking allows you to gear up your business for expansion in that connecting remote workers is much simpler, meaning you can attract the top talent independant of your business geographical location. The same is also true when it comes to phone numbers which makes it possible to include international phone numbers, providing your business with a local presence in international markets.

More functionality: Unified Communications

Another benefit of SIP that is often overlooked is the increased functionality that combining voice and data in one network allows. SIP and all-IP technologies form the basis of Unified Communications and All-In-One Cloud Business Communications solutions, such as PASCOM ONE. By leveraging the benefits of all-in-one IP based solutions, businesses can significantly enhance efficiencies and drive employee productivity whilst achieving a more attractive and professional image within both the employement and consumer markets.

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Workplace Mobility

Mobile working is now the norm and SIP trunking is one of the most effective technologies to enable seamless mobile employee and remote team integration. Just as SIP allows businesses to build the Unified Communications solution, it also enables simpler, more effective integration of mobile devices such as laptops, smartphones and tablets. Cloud communication providers and VoIP providers that offer 1st party VoIP apps such as the pascom VoIP apps for Desktop and Mobile, provide remote users with quick and simple access to all their business communications channels, from softphones for voice to Instant Messaging and web meeting tools for Chat, Team Messaging and Video meetings.

Beyond this, incorportating SIP softphones on mobile devices are also excellent for improving your business continuity and contigency planning as they can be connected to mobile data networks and Wifi, allowing users to continue working productively even if the office loses it’s Internet connection.

Business Continuity

Just as SIP bolsters mobility and therefore Business Continuity, there are other aspects of SIP that allows you to make your business more robust and agile when reacting to changes. Worst case Force majeure scenarios such as extreme weather or as seen with the Covid pandemic, can force businesses in to a position where they need to have the tools to adapt immediately.

SIP trunks registered to a cloud communications platform are accessible from anywhere via the Internet, so even if one site goes dark, another site can still be online and remote workers will most likely not be affected at all, allowing your business to continue operating as normal, making SIP trunking and Cloud technology essential to any business’ disaster recovery plan.

Cost Savings

Finally, SIP trunking has the potential to save your business a significant amount of money. All of the above benefits will help your business become more profitable by helping prevent unpredictable costs, downtimes and wait times. However, SIP trunking is also cheaper than traditional telephony. First off, the cost of acquisition is low compared to traditional telephony as no physical lines are required. Internal calls within an organisations business phone system are free and international or long-distance calls are significantly cheaper as they are routed over the Internet.

Additionally, SIP trunks offer flexibility in terms of scaling the number of channels you need, allowing you to pay for what you use. Moreover, traditionally telephony has been billed on a per-minute basis and did not included minute bundles. This first began to change with mobile contracts within the world of the end consumer and SIP has now changed this again for business customers with the addition of flat rate packages including landline and mobile network minutes.

4. Example SIP Trunking deployments

Legacy Analogue PBX

If you are looking for a quick and easy way to start transforming your business communications, but do not want to completely do away with your analog on-site telephony system infrastructure, then SIP trunking is a good option.

Be warned though, this will involve upfront investment in Media Gateways that are required to make your old legacy systems compatible with SIP technology.

Onsite IP enabled PBX

If you are switching to SIP trunking but already have an on-premise IP PBX solution, then you may potentially need to invest in your network, Internet connectivity, Session Border Controller and Quality of Service (QoS) infrastructure in order to ensure VoIP security and audio quality.

Cloud PBX

Depending on your circumstances and requirements, it would probably be more prudent to switch to an all-in-one cloud phone system (Cloud PBX) such as pascom ONE.

Even if you want to keep your existing phone numbers, all you need to do is port them to your new VoIP provider. The process is relatively painless, but you will need to plan approximately 30 days for it to be completed. In the meantime, it is possible to use features like CLIP no screening to transmit your existing Caller ID numbers when making calls and redirects can be used to make sure your customers can still reach you before the switch has been successfully completed.

5. Why should your business switch to SIP trunking?

From the above benefits, it is clear to see that businesses can immediately benefit from SIP trunking. With limited initial investment being required and hardware acquisition and maintenance costs effectively being eliminated, businesses can start enjoying the benefits of SIP trunking immediately when it comes to cost savings.

But there are long-term benefits to. By enabling remote working, SIP trunking helps make your business more flexible whne it come to accomodating the needs and requirements of the modern worker in terms of HomeOffice, remote working, and even how employees prefer to communicate (phone, chat, and video) and on which device.

Furthermore, by combining SIP trunking with Cloud based Unified Communications in a cloud business phone system with user-friendly mobile UC VoIP apps on employee devices, SIP trunking provides business owners and IT managers with a central application for all their business communications. This gives them the opportunity to improve customer care by eliminating information silos, streamling communication processes and giving employees to connect with customers from anywhere.

Finally, another reason to use SIP trunks is to help grow employee satisfaction. By providing your team with everything they need to work flexibly and effectively from anywhere, your employees will be able to more easily find a health work-life balance which in turn grows their motivation and this can only have a positive effect on your company’s bottom line.

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6. Are there any disadvantages of SIP Trunking?

As with everything, there is inevitably a downside to switching technology. SIP trunking is no different, but with a little forward planning and investment, the downsides are easy to overcome and the long-term benefits easily outweight the minimal expenditure required.

Network & Connectivity Issues

One of the main benefits of SIP trunking is the bundling of voice and data into one network. However, this can also be a disadvantage as having everything run over one network can put an extra burden on your existing network and Internet connection. This means there is the potential risk of suffering from network and connectivity issues due to the higher capacity and bandwidth requirements.

Potential additional infrastructure requirements

If you choose not to go down the all-in-one cloud route, you will have to invest in additional infrastructure.

This may include solutions for:

A VPN may be required in order to allow remote workers and offices to securely connect to the centralised communications platform. While the SBC also performs this role, it may be wished for as another security layer.

A Session Border Controller adds an additional security layer to the SIP traffic and acts as an authentication protocol when routing SIP traffic to and from your business phone system.

Quality of Service (QoS) prioritises real-time network traffic that is sensitive to network delays, such as voice and video streams, to ensure that they are handled with more priority over less sensitve network traffic, e.g. PDF downloads etc.

In order to overcome network capacity issues, it may be necessary to upgrade your Internet connection and invest in new network infrastructure, particularly if your existing network infrastructure does not support enabling QoS.

Moreover, to monitor and identify and future potential network issues and QoS improvements you may need You may need to invest in Application Performance Management (APM) technology.

7. SIP Trunking FAQs

How many SIP channels will I need?

The number of SIP channels that your business will need depends on the number of simultaneous calls that your business makes and receives.

A good business communications solution / SIP provider will be able to help you with this calculation.

Does SIP trunking require higher bandwidth?

Since all your voice and data are transmitted over the same network, it is likely that you will need more bandwidth compared. The amount of bandwidth required for SIP trunking depends on the number of concurrent calls (simultaneous calls - i.e.calls at the same time) your business makes and the codec used. As a general rule, each call requires around 100Kbps, so if you make 2 simultaneous calls, you will require 200kbs bandwidth.

What factors affect SIP trunking bandwidth requirements?

There are a number of factors which affect SIP trunking bandwidth requirements. These include the number of users, the audio codec being used, the Internet connection quality, and the type of traffic on the network.

Choosing a provider that supports HD codecs such as OPUS and G.722 will help ensure higher audio quality, while QoS will prioritise voice traffic over less sensitive network traffic to help minimise quality losses.

Are SIP Trunks reliable?

Yes, SIP Trunking solutions are reliable as SIP trunking providers will have inbuilt redundancies, DDoS protection, and active monitoring solutions in place.

Can SIP Trunks work with existing phone systems?

Yes, SIP Trunks can work with most modern phone systems, and Gateway adapters are available for legacy systems.

How can SIP Trunks improve flexibility?

SIP Trunks allow for geographic number portability, remote working, and scalability. For maximum flexibility, it is advised to choose a SIP trunking provider who also offers cloud phone system solutions as an all-in-one solution, as this provides the added flexibility of Cloud services, SIP and all for one low monthly cost.

Does SIP Trunking support emergency calls?

Yes, SIP Trunking providers are required to support emergency services calls, and businesses should always test their emergency capabilities before implementation.

How can I choose the right SIP Trunking provider?

Businesses should evaluate providers based on their pricing, quality of service, reliability, support options, and additional features such as international calling and routing. Researching reviews and contacting potential providers can also help to make an informed decision.

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